Added: 3 years ago
From: patrickJMT
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  • I swear math is like magic...

  • @kenikozo it is pretty amazing stuff. i wish i was smarter and less lazy so that i understood more of it :)

  • This video definitely helped a lot! I like how you got right to the point instead of drawing out useless information like some videos!

  • @katherine55100 always a fine balancing act between showing too much and showing not enough. :) i do my best!

  • hopefully u can do more examples on this type of questions

  • Khana < rootmath < Patrick JMT

    That's just how it goes...... ;)

  • this one is hard :(

  • I'm in calc 2 here at UMass and my professor is not the best at explaining this. But you go into detail and thought process for each step and because of this video I now understand what my professor has been trying to teach us for the past two weeks. Thank you.

  • wonderful. You are going to heaven my friend.

  • 4:30 how can you randomly put x^2/2 on the right side without doing it to the left?

  • @desertfox1792 Look carefully. On the right side, the 2 in the numerator cancels the 2 in the denominator. What is left is exactly equal to the left side. Hence, no error ;)

  • For the series, it starts at zero. So the first term would be (2x)^0 = 1. If you take the derivative of the series, wouldn't it mean the same thing as taking the derivative of the values? The derivative of 1 would be 0. Therefore n should still start at zero. Correct me if I'm wrong.

  • Hey Patrick, do you have a video where you find a definite integral? The only question I have is say that our limits on our integral are 0 and 0.2. After finding what the integral is, do I plug in 0.2 in for x or n? Please reply asap bc I have a test tomorrow morning. Thanks!

  • Seriously?!?!?! Patrick, you are the lifesaver of upper level mathematics. My book "explains" this step by step but they forgot we speak english, not some foreign out of this world language, thus the reason why I couldn't do my homework for almost a week of trying to learn this stuff. I watch this vid once%2φ

  • Hahaha, I thought my phone was ringing and then the akward silence when you weren't speaking made me realize it was yours. Made me feel like an idiot, lol.

  • Didn't make sense.. till i started solving the problem too.

    Any idea how to solve for the interval of convergence ?

  • @MrSoysauce2rice plug the radius of convergence that you got back into your originial power series and test for convergence or divergence using one of the tests. If its convergent, you put a bracket and if its divergent you put a " ( " . So, its a x,y point where x = -R and y = +R .

  • You are awesome! I was just about to give up on my homework, but I think I get it now. Thanks for putting this up!

  • Thank you so much Patrick, your videos are so helpful.

  • How do you know when you move the lower bound of the sum upwards or downwards? Like when you differentiate or something, you bring the lower bound n (of the sum) up one or so.

  • Oh my goodness! I started laughing so hard when I heard the phone start to ring and even harder when you ran to silence it. Those footsteps were priceless. By the way, did I give you that t-shirt idea or were you gonna do it anyway?

  • shouldnt that be a -2 when you take dy/dx of (1/(1-2x))

  • Patrick...How do we go about finding the first few coefficients for a power series...

    i.e.

    c0

    c1

    c2

    c3

    etc...

  • really wish i found these earlier! 

  • post more examples plz! thanks for everything!!!

  • corroborate with Sal and Bill Gates, you guys not only can, but WILL change the world.

  • @runback1983 ha, i dont think bill gates is sitting around waiting for me to call : ) but thanks for the encouragement!

  • @patrickJMT We would support you in this endeavour!

  • @scilabo ok, go tell them! not much i can do about it

  • @patrickJMT I've been watching Khan Academy for the last few months. You really picked up where he left off in the Calculus series. I'm totally a Patrick JMT convert and tell everyone in my calc class about it. I really think if you were to collaborate, it would take the educational community by storm. Thank you for all you do here! I will definitely donate to the cause as soon as I'm not a terribly poor college student!

  • @mytwohands thanks for spreading the word : ) i have emailed him but i do not think he is interested : )

  • @patrickJMT That's a shame. Maybe he is happy how he is now with his big pay check from M$

  • @mytwohands epic. i love Sals videos. Ive survived engineering school

  • @patrickJMT You were there for us in some of our darkest and most desperate times of need. You are helping future scientists, doctors, engineers(me), and mathematicians.  These are the people who are going to be forging a better path for humanity. You are helping mankind progress and the world will be better for it. Thank you Patrick.

  • Uh,this one was really hard :P Had to watch it like 3 times but finally i got it ^^

  • Thanks for the video. That was pretty cool seeing how you could manipulate a function to get the power series representation. It probably does take more examples to get used to it, and I'm all for more seeing more examples.

  • the phone call and caterines phone number distracted me... cant focus anymore.

  • i see what you did at 3:00, you differentiated the summation itself. what we were taught to do was, write out a few terms of the series, differentiate each, and find a pattern so you can write it in general form.

  • Excellent videos man! Like many others I'm stuck teaching myself because my actual professor, and I use that term loosely, is useless. Thanks to you, and others like you, I'm actually making sense of this stuff. So thanks again, and if possible I wouldn't mind seeing some more examples on this subject. Cheers!

  • Educator.com, my ass!

  • just want to let you know that i love all your videos! thank you so much!

    But I've never been this lost in my entire life! when do you integrate it and when do you differentiate it?

    or how do you know which one to do? thanks

  • Haha i looked at my phone when i heard yours ring.

  • Why didn't you pick up the phone? I just wanted to say how awesome your videos are!

  • Some needy Calculus student on the phone, sounds like.......

  • was that Cathron calling you :P

  • @imkaneforever lol i think it said cathreen unless it was his robot girlfriend...

    Cathreen + tron = Cathron. :O

  • lol i saw the number even tho you tried to hide it

  • I still dont understand when to start the series at 1 or 0.

  • @mikegovikes try writing out the series for the first few terms and see where ur differentiated/integrated series begin

  • @mikegovikes

    I think that when you derive a series that starts at 0, you need to start at 1 instead of 0 for "n" in order to start the series off with a constant

  • I love you so much <3

  • I'm havin a hard time understanding the concept

  • derive the power series for g(x) = (1+ X^3) ^(1/2) and put into sigma notation i need help on this problem

  • THANK YOUUUUUUUuuuuuuuuuuuuuuuuuuuuu­uuUuuuuuuu

  • Hey, for the second question you did; what if you got c to equal a number.. then if you subracted it from the equation you got to make it look like the original question it wouldn't be a power series anymore right? so what would you do? and btw thanks so much patrick for providing us with so much help.. it means a lot to me and everyone else.

  • Just wondering... do you know when to change the n values? like n=0? n=1? when to change it? because I have no idea when to change it..

  • would love to see more examples of all types of series

  • U're right! u might have to take a look at the video a couple time to understand :)

  • Comment removed

  • hey Patrick, I really wish you would've done a easier example before this one.

  • Hi great videos, As of last week I started studying "sequences and series". Again, the branding chosen inappropriate and unnecessarily confusing , not distinguishable at all. I would leave "sequences" as it is but would refer to "series" as "add-series" or better yet "add-sequence or sum-sequence" simply because now, in the word the clue of summation already has been giving in the initial descriptive sense.

  • how can I find the radius of convergence? I'm confused.

  • @abthurd you should watch the video about: radius of convergence

  • you're such a great help, dude.

    God bless.

  • Thank you so much for connecting the dots that the calc book doesn't.

  • Please do more examples, this is pretty next level compared to the other stuff

  • How do you know when you should differentiate and when you should integrate? What do you look for in the problem?

  • DId you go answer the phone? LOL that was funny!

  • Hi thanks for the vid. A question though. Why dont you shift the index by replacing n with n-1 in integration, much like how you replace n by n+1 in differentiation?

    Thanks in advance

  • Dude you are awesome

  • thanks for your videos!!! they really helped me out!

  • wow this is intense o.o

  • i've been watching all of your calculus videos since my midterm, since then my grade has gone up TWO LETTER GRADES. Tomorrow morning is my calculus 2 final and if i make an A on it i make an A on the course. i dont wanna jinx myself but ive been studying like crazy with the help of your videos so i feel good. If i get an A i will donate my life savings to you and name my first child patrick. no lies.

  • @peslie25 ...even if its a girl?

  • Could you please do a few more examples? :)

  • I don't quite understand why 2^n inside the sum is treated as a constant...doesn't it change with each term? Isn't x really the constant here?

  • @Jawshooah it is a function of x.

  • @Jawshooah to be more specific, it is on respects to x

  • @Jawshooah I was going to ask the same thing. I really couldn't understand how 2^n was a constant as well. But I guess since we're taking the derivative with respect to x, that would truly make 2^n a constant. Otherwise, if x was the constant, the derivative of x^n would not be nx^(n-1) but x^n*ln(x).

  • wouldn't that series diverge?

  • i need help; with a sine and cosine to represent them as a infinte sum.

  • Ok, this is starting to make sense.

  • you've been helping me ace my calc quizzes every week with your clear examples and easy to understand explanations! THANK YOU SO MUCH!!

  • @curbsidelexi no prob, keep up the good work

  • I have a question, how do you know when to differentiate and when to integrate?

    I noticed you integrated for the inverse tan function, but then integrated for the other.

    how do you know?

  • Wait.. So, Patrick. You're saying you started out with Pre-calc in your sophomore year, of COLLEGE?? Dude.. I've been taking calc since my sophomore year of HS and it still intimidates the hell outta me. Your videos help to clear a lot of it up though. Thanks!

  • @iYoungJ89 yes, i believe it was my sophomore year (actually, it may have been the summer between freshman and sophomore year). but i came to math relatively late in life i think

  • hey patrick.!

    I was just wondering what happens when you find the value of C, where would C be, on the right hand or left hand side of the equation?

    thank you for the video, it super duper helps!!! :)

  • Thank you so much for putting up these videos, as a freshman in college in calc two with a test on Monday, I really appreciate your explanations of series. You're the best!!

  • please more examples!!

  • Need more examples on differentiating power series!!! thanks.

    

  • THANK YOU! I have a Cal 2 test tomorrow and this along with ratio test was so confusing in the book. Your explanations were crystal clear

  • You saved my life man, my parents wouldn't let me play Starcraft 2 because i couldn't do my homework on this. Thanks to you I was able to complete my homework and now I can play Starcraft. You are the best ever!

  • hey... Patrick in your second problem Shouldn't your C be in the right side of the integral....

    well, Thanks for the videos...

  • 2:40 s something, shouldn't the derivative of 2^n = 2^n.ln2?

  • @raiden233

    yes but he is Taking the Derivative with Respect to X.

    And when Integrating you integrated Also With Respect to X (dx)..

    

  • ommmmgggg wtf was that?!?!?! All that was just like.....woooaaaaahhhhhh, so crazy. I didn't understand what my professor was talking about when he did this lecture this morning. But after watching this, I actually kind of understand it now : D. I just have to watch this a couple of more times to fully understand everything. Thank you for making everything much simpler to understand!

  • Patrick! Could you explain more why you make the n=1 at 2:39?

    I still don't understand why you had to change it from n=0 to n=1.

    THX!

  • do you have a lesson about the matrix inverse? The Gauss-Jordan Method?

  • Patrick! What can I say, man, except you rock! I am taking an online calc II course with very little contact with the instructor but need to the course to get into my grad school that starts in sept. I would, without a doubt, be miserably failing this course without all your videos. You shine light in dark places, bro. Much appreciated!

  • @steelblue831 i would have failed this class if i had to do it online : ) so keep up the hard work!

  • thanx u r the man

  • Great video! Thanks so much for all your help!

  • This video is the best! Thanks so much for all your help!

  • hey man, you the bomb! great work teaching this stuff.

  • this is the first topic in calc so far really tripped me up. thanks for all the time you spent on this chapter

  • my exam is tmmrw, can u write it for me?

  • if you integrate the original f(x) then find a power series representation for the integral of f then differentiate that power series you should get the same answer?

  • hey i really love your videos! is it possible to do one on using a power series to approximate a definite integral to decimal places? thank you!!!

  • marry me

  • click his ads!!!

  • @mahtab840 what ads?

  • why at 4:18 did you do that multiplication. where did the two's come from?

  • I'm sorry but I still don't understand what happens with the plus C after you integrate..how DID you managed to get rid of it? From the video, it seemed as though you took an arbitrary value of x and solved for C at that point..sorry if this doesn't make sense..I just want to know what happened with that +C after integration and how to approach similar situations in questions

  • this was unbelievably helpful, thanks

  • my school is absolutly not preparing me for college...especially in calc...what happens if I screw up in college bc of a lack of knowing calc before I get to college?

  • well, you, like many others, will have to either retake it, or taking some to prepare you for the class.

    this was the same sh*t hole i was in... my school was a total joke. i skipped about 50% of my days as a high school senior but still made A's in everything.

    i had to start with precal myself in college (sophomore year)...

  • @patrickJMT I am studying to become a math instructor. What would make calculus better in a classroom? Although I have an excellent professor, I do most of my learning on my own and with the great help of your videos.

  • @YBPhotoeditor06 You can always go to a junior college to do generals(it's convenient bc its cheaper) and in 3 semesters(algebra, trigonometry, calculus 1), you can be good to go in calculus 2, 3, linear algebra, ode, proofs, etc.

  • @YBPhotoeditor06 dont worry about it. i didnt take calc in high school, i didnt even take math my senior year. i made an A in calc1 at LSU. although i studied my ass off . it just takes a lot of work, but you can do it

  • @YBPhotoeditor06 Your not prepared for college until about a month in. lol. don't stress.

  • why was there a random annotations box with x's at 2:20

    did you do something wrong that i didn't notice?

  • i have no clue why those are there... (or were therE, cause i just removed them).

    thanks!

  • thanks

  • the proof of differentiation of power series and Abel's Theorem are very interesting too.

  • LOL it'd be funny if you picked up your cell phone while doing the video

  • thanks man appreciate it

  • Please do more examples!!!!

  • @typeInLIV can you ask him in a more polite manner? -_-

  • @t3nd10usx Hmmm.... Notice the PLEASE at the beginning of my request. Let's define please. Please: used in making polite requests and in pleading, asking for a favour, etc. Example: "please pay attention" So, PLEASE go somewhere w/ that.

  • can you do examples of finding the radius of convergence after doing differentiating and integrating power series? Thanks.

  • for the problem in which you differentiated 1/(1-2x), how would you find the radius of convergence of that? Is it just one? I'm doing my math homework now and I had a very similar problem however, it was telling me that the radius of convergence was not one.

  • How and where did dividing x^2 by 2 come about?

  • darn your left-handedness!

    but you're still great!

    thanks for all the help.

    you're better than any tutor.

    :)

  • can you do more examples of differentiating and integrating power series?

  • can you write x^2 / (1-2x)^2 as

    (x^2 / (1-2x)) * ( 1 / (1-2x))

    then just write it as a power series and differentiate

  • thank you so much.  my calc 2 professor isnt the best and the book doesnt explain anything. you have helped me a great deal

  • Why is it that when you differentiate a series the index of summation increases by one, but when you integrate a series the index of summation does not change?

  • well, it depends.

    expand out the series expansion, differentiate, and put it back together and you will see

  • yo patrickJMT, that was indeed a gr8 help for my finals, thnx a ton man. I needed this help bcz I missed the class for this lecture and this tutorial saved my time , thnx a ton once again.

  • in first example if you plug in x=1 - the series will not converge. i think you should have said that the representation is good only in some region.

  • yes, you are correct, i should have emphasized this.

    when i made the video, i was focused on the mechanics of the problem

  • yes, you are correct that i should have emphasized this.

    i was focused on the mechanics when i made the problem.

    i also made this video for a student that i was tutoring at the time, and she was aware of the interval, so i did not think so much about it : )

  • still your video is very good. and i see you are lefthander, jist like me)

  • In another video you made, you explained that abs(x)<1 is essential for convergence to occur

  • nvm

  • i think you did this one wrong....when you take out the (-2x)^2 you keep it as (-4x^2) but it should be (-2)^2 * x^2 giving +4x^2 so the (-1)^n shouldnt be there....correct me if im wrong...

  • Man patrickJMT... the way you simplified that last problem... I would've never thought of that...thx a lot for your vids..

  • sorry again about the previous post. im stupid. but im confused about the constant part and why that makes it start and n=1 instead of 0

  • I think it is because if you write out the series before the derivative is taken you'll see a constant at the front. when you take the derivative of a couple terms, it'll still have a constant and to you have to set the series notation for the derivative to start with a constant so that they agree...I think...you should wait for confirmation of others.

  • Question, Why is the derivative of 1/1-2x become 2/(1-2x)^2? I took the derivative to be -1/(1-2x)^2

  • Solid.

  • Best. Teacher. Ever.

  • Why does my instructor make this so complicated?!? Why can't they just show me examples like this? It's not like your making this easier than it really is, because I've been doing 95% on my tests based on these videos.

  • glad that i have been able to help you : )

  • Regarding changing the index, it has to do with the fact that if you differentiate a constant, it becomes 0. So the first term is gone, so you change the index to reflect that. As for the radius of convergence, all power series converge at x=c if they converge at all. Since c=0, in this case, he is using that. The important part here is simply that he needed one point to solve for C. You can use any point, I believe, and it should work. 0 is just the easiest in this case.

  • The most enthusiastic teacher I've ever seen. You turned off your phone, which rang during the seminar to keep it going. Even my passionate teacher doesn't do that. PATRICK JMT ROX!!!!!!!!!

    Anyway, how do we show that S(1/n) (summation of 1/n as n goes from 1 to infinity) diverges extremely slowly? We can't do it using Test for Divergence.

  • well, you can show it diverges through an arithmetic argument; to show that it diverges 'slowly'... what does 'slowly' mean? i agree.... if you add up terms... lots and lots and lots and lots of them, you still getting a pretty small number

  • your video is great/ I wish you were my calc teacher!!!!!!!!!!!! you should definitely think of moving to Illinois and teach math here!!! *around 2:50 I am kind of confused too D: can anyone explain why he changes the index 0 to 1? D: *

  • I am a little confused... I have seen this a couple times so obviously I am missing something... you say that the derivative of 1/(1-2x)=2'/(1-2x)^2 now... wouldn't you use the quotient rule? 1'(1-2x)- haha nevermind

  • My brain melted a little, but I think I'm getting the hang of this now.

  • this part can be a bit tricky

  • you are left handed (me too)

  • I think it's self explanitary. :[)

  • Your videos have helped me so much. I'm a freshman in high school and have just taken the calculus placement exam and it was easy thanks to your help! I'm still very nervous because I'm waiting for the results.

  • cutedude22: Nope, it's clarinet lessons.

  • answer the phone!

  • thaaaaaaaaaaaaaaaaaaaaaaaanks

  • i think im in love...

  • who with?!

  • for the 2nd prob, it could be a little easier if you substitute u=2x and then plug it at the very end right?

  • hey i was just wondering do ya ave any vid sshowing how to do the recurrence relation?