Completing the Square in 60 Seconds

[Rienclue]

i have a question. How to find the values of x in x(2x - 7) = 0

please, i really really don't know how to find it. I hope u can help me . Thanks..

[carlcampbell7]

@Rienclue x(2x-7)=0

x=0 and 2x-7=0

so x=0 and x=7/2

[ThunderCatMovies]

88 seconds -_-

[zoobat20]

the real answer after finding the square should be x= 0.35889894 and x= -8.35889894

[willghass]

@zoobat20 That's if you solve it for x.

[TheXxLennonxX]

Made soo much harder for yourself

[zombiejesus94]

this was 88 seconds..............

[yashsoldier]

suck up the squares Lol. but nicely done

[jflint5]

*completing the square in 87 seconds

[Gbiney]

you haven't completed any square! you still have to square root it.

[stemcgolf]

Scribble out the 8x and then suck out the square?!? Haha Your funny. God help the students.

[SimbaVScar]

@stemcgolf lmfao right? god i have a math final in an hour and this guy stopped like halfway my answer was -4 plus/minus square root of 19

[135meredith]

wow... im a freshmen and this totally just screwed me up for my math test tomorrow. THANKS A LOT INTERNET

[TheMolotovTaco]

@135meredith Let me help you bro. watch?v=gzm-uhj06q8&feature=ch­annel_video_title

Even though your math test is long gone, you will want to watch this. Save the channel too, it's absolutely fantastic for studying and getting past terrible lectures.

[135meredith]

@TheMolotovTaco I don't mean to sound condescending or anything, but there is no link, dear sir... I'd love to see what you've got to though.

[FYIitsnotme]

This is actually terrible. srsly. I'm doing A-level maths and came here just to double check what my Teacher told me and this fucks up my understanding of it. Screw you!

[pradame786]

@sign333b you try to divide the coefficient of whatever x^2 has to one like 2x^2 divide 2=x^2 and just use his method.

[sangng1993]

you're not done... it's incomplete... your teaching is invalid .....

[tireironman]

you'll get the right answer by doing it this way, but you wont understand why.

[sign333b]

what if the x^2 has a coefficient bigger than 1 ? :P thats when it gets shitty

[MrPostmanPhat]

@sign333b When the coefficient of x^2 is larger than 1, x^2+bx+c can we rewritten as a(x+p)^2+q. i.e

Completing the square for 2x^2+8x+3;

a) 2[ x^2+4x+1.5 ]

b) 2[ (x+2)-4+1.5 ]

c) 2[ (x+2)-2.5 ]

d) 2(x+2) -5

[MrPostmanPhat]

@MrPostmanPhat i forgot the ^2 for the brackets :O!

[kidhbailey09]

nooo wayyy dude wassup with the messy hand writing? Back to YourteachermathHelp.......

[jocsoncedrick]

my LAST ANSWER IS

X=-4+OR-SquareRoot of 19

[ninjasasuke123456789]

you sir are genius!!!!!!!!!!!!!!!!

[DragonClawRusher]

correction : (x+4)^2 = 19 is actually properly factorized to x=-4+or- the square root of 19 =P thumb this up so he can see

[inotpigkong]

what about 2x^2 - 12x+11 and bringing it to y = a(x – b)²+c form.. do you have an answer for that?

[joannafreethinker]

HELLO- it is to cut the point- not teach subject matter to beginners. I am in calc II and needed a quick refresher- this was perfect... if you don't see what happened here you shouldn't be watching this video!

[krustygerbil]

this guy isn't wearing any pants lol.

he's a well known rapist!!!

[runhorun]

@krustygerbil why did he give you a few good pumps? ... seems like you know alot about the man.

[rickster326]

Your Cool!

[caraannie14]

I LOVE YOU. you forgot to finish it though... youu have to do the square root to both sides and put a plus and minus before the right side of the zero and solve for -the # and +the #

[beautifulpianoforte]

year nines are SUPPOSED TO know algebra.. i did it in year eight lol.

and did anyone else notice when he said suck out the ^2, he did a ^3 instead, ? lol :P

[maxmooney]

My ninth graders would NOT understand this at all! (Because it only makes sense if you already know Algebra.) Epic fail. Sorry.

[MikeHawk1234567890]

Well done! 

[noahwelcomehome]

Lol I don't think so.

[neilz678]

mind blown u should teach the universe math

[slimpat16]

he didnt complete complete the square. the final answer should have been

x = - 4 + or - the square root of 19

[Uaxis]

@slimpat16 Well no, he did. He just didn't give the final solutions.

[mohoho111]

this is more like 88 seconds lol.. Jks

[MathZar09]

no! no! no! Ignoring the 8x just gives the impression that x^2 + 4^2 = (x+4)^2 WHICH IS FALSE! That is a major concept that I spend a lot of time in calculus trying to get out of my students heads! SHORT CUTS ARE BAD! Do not do this!

[Uaxis]

@MathZar09 I think if you got more personal with each student, it would've taken less time to get it out of there heads.

But I'm not here to judge.

[steveecker]

@MathZar09 It's not an invalid shortcut, using that only matters because the 8x is the sum of the 4s. At the point where you square the polynomial etc, addition and subtraction to result in the 8x isn't an issue. He should, of course, also erase the ^2 by the x, because he'd be rooting (x^2 + 4)^2, rather than (x+4)^2. So I agree with that. But if the equation is in standard form to begin with (no ^3s etc), it won't ever be an issue... (provided people can keep track of their signs and powers)

[GenericPlaque]

@MathZar09

That's simply because he forgot to mention that this is only applicable to perfect squares (a^2+2ab+b^2), the result of (a+b)^2, which is the whole point of determining (1/2(2b)^2, or b^2. It's not really a magic shortcut, and if the concepts behind it are actually taught with the material it's a very useful tool for quadratic equations.

The whole methodology of "math in 60 seconds" is a mistake, though.

[ToshPointNO]

@MathZar09 No..it gives us the impression that x^2 + 8x + 4^2 = (x=4)^2

[zenninbor]

@MathZar09 This is a great video for someone who needs a refresher, that's all. Great video.

[pooran411]

@MathZar09 you with many 'thumbs up' stopped me to watch this video

[TheMolotovTaco]

@MathZar09 The biggest issue is that kids like me may not understand HOW and WHY the 8x is being "ignored." When I was taught this, I was told to ignore it and I completely shut down on the concept. It made no sense. Now, after a KhanAcadmey video, I see that it's a simple (x+a)^2 concept, and I can understand how the 8x is there and where the (x+a)^2 comes from.

I agree, teaching the concept with shortcuts is detrimental to learning, I have experienced this first hand.

[dragooner4]

sweet i like how he said you can just ignore 8x, makes the the equation a whole lot more easier to understand

Thanks

[pinkcrave320]

PLEASE COME TO MY SCHOOL AND TEACH MY MATH CLASS

[1234LMAO12345]

this is only half done, you have'nt fully completed the square

[PoliticalJohn]

Your explanation causes me to rage at EVERY damn math teacher I have ever had. Why couldn't they explain it that easily?

[FuzzyOpposum]

@PoliticalJohn Because that way doesn't teach you what you're doing.. xD

[pencilgerman]

x= plus-or-minus radical 19 - 4. Just sayin'.

[MsMadame]

Your incredible!

[frenchfriesidiot]

I've been watching PatrickJMT's and I know he did not finish completing the square. One good tip I picked up on this video nevertheless

[Jasonater94]

to bad he didn't completely complete the square.

[L4Maulers]

LOL the hell.

[ExMarKaSpoT]

awwwww fail, remove the intro and ending to complete the achievement :P

[abagonboys]

shitting fast, I need more examples to understand it

[AtomicHercules]

When you square both sides of the equation you have to put +and - after the = sign. you left that part out. it would be marked wrong on a test.

[L4Maulers]

@AtomicHercules You only put the plus-minus sign there if you're actually solving the equation. In this example, he wasn't. Therefore, he had no need to put that sign there.

[AtomicHercules]

@L4Maulers shit man, you're right. when would you ever be asked to SOLVE it anyway?

probably almost every time you have to do one. dipshit.

[L4Maulers]

@AtomicHercules Yeah, so you're never asked to FACTOR it. SOLVING is the main priority. Do you need to retake Algebra 1, "dipshit"?

[AtomicHercules]

@L4Maulers A squared plus B squared equals fuck you squared

[L4Maulers]

@AtomicHercules Lmfao nice comeback kid. Go back to grade school before you start acting like a smartass.

[AtomicHercules]

@L4Maulers using the above video, your mom and I were able to complete the 69.

[L4Maulers]

@AtomicHercules Doesn't even make sense.

[AtomicHercules]

@L4Maulers you just flip around and suck each other's genitals. it's not that complicated really. 

[L4Maulers]

@AtomicHercules Bro, just grow up and admit your mistakes.

[AtomicHercules]

@L4Maulers bro, you don't know shit about shit. thanks for taking time out from fucking your fist to comment here. asshole.

[L4Maulers]

@AtomicHercules LOL back at ya.

[AtomicHercules]

@L4Maulers congrats, you just completed the LOL square, cocklick.

[L4Maulers]

@AtomicHercules If you're gonna TRY to insult someone, at least TRY to make sense. Don't even know wth you were saying for the last 5 posts lmfao.

[AtomicHercules]

@L4Maulers no man. L MY fao, dickcheese. the only math you understand is your ass divided by 1 cock equals :D

[SuperHistorylover]

thanks

[lordthorpez]

It's short! It's good!

[qmcgee11]

smart ass 

[SuperCrazyAngela]

Sigh, to all those who don't understand, (including me) just use the quadratic formula. A few steps more, but all you're doing is plugging in a, b and c variables. Trust me, its sooo much simpler. :)

[comicreaper]

@SuperCrazyAngela yeah but my test requires me to solve completing the square.

[lindithium]

Man you are a life saver! I have been looking for an example like the one you worked and you were the only video with one. You made it look so easy!  Thank you! Thank you! Thank you!

[eclipse245]

No the 8x doesn't disappear. He skipped a step. You are supposed to divide the 8x once again by 2 or "half" which is the number you will put in the bracket, in this case "4". And then continue on with the rest.

[ghkerhnkjern]

duuuuhhhhh...i dun geddit...

[ppoem123]

WTF happened to 8x???

Wh do you need to take it out?

[penzorc]

okay quicker and 10x easier way you strat with x(squared)^2 +8x -3 = 0 you simply half the coefficient of the second x and put it into brackets (x+4) ^2 then because you halved the coefficient of x you have to take away 4 ^2 which is 16 so (x+4)^2 - 16 - 3 = 0 = (x+4)^2 - 19 = (x+a)^2 - b

[kouriskiii]

@penzorc oooft

thanks <3

[MattAbbott92]

@penzorc thats the formula i use :D so much easier :P

[Arkile]

where does the 8x go?? i dont understand? it just disappears?

[hulaxhoops]

thank you. a lot.

[aitsamoes]

there is no need to take the three to the other side because ur gona need it later when u do parabloas and are asked to put it in the y=a(x-h)2+k

[cinderellasCurse]

uh such a simple and uncomplicated way of doing it, thanks!

[Vonzi0000]

(x+4)^2 =(x+4) (x+4)= x^2 + 8x + 16

[Vonzi0000]

his way of explaining is confusing for me the 8x doesnt just vanish because

(x+4)^2 =(x+4) (x+4)= x^2 + 8x + 16

x^2+8x+4^2= 3+4^2

>>Proxy-Connection: keep-alive

Cache-Control: max-age=0

0(x+4)^2= 19

[JCLois77]

this is horrible. just giving tricks does make anyone learn.

The 8x disappears and you suck out the exponent. Eek!

[mattyr2k8]

horrible way of doing it imo :\

[turntablist2]

Thank you!

I have been struggling for hours on this and have my assignment due today.. its 2pm. sigh.

[dxsam3]

this was awsome thank u !

[TheGreenDuck3000]

wait what if its not just x^2 by its self but say... 3x^2

[TheGreenDuck3000]

wow thanks got a test tommorow an i think you saved my ass lol

[kutieJ]

i was taught to do (x+4)^2 at the beggining but that still works.

[Johannady]

i missed this lesson since i got late!!

thanks teache math crazy!!(-^_^-)

[jk1546]

thank you sooooo much. alot easier visualy seeing it then reading in in any text book...

[Sweetxhartx3]

really helped. thanks =)

[manyobbo456]

this vid saved my ass for the GSCSE maths i had yeaterday

[NatReading]

I love you, thankyou so much - you are the best math teacher i have ever seen!!!!!!!!!!!!!

[Poree93]

Really good & Clear Explanation! Really helped!

Thanks :D

[ray098]

FANTASTIC

[chandikarocks]

CRAP

[psITSmandy]

Thank you!

[mephatboi]

nice!

of course, this is the easiest case

u could've used a fraction in the x term or had a constant u had to pull out

like 4x^2 + 8x + 1 = 4(x^2 + 4x + __) + 1

but due to time constraints yada yada

[stl1982]

Really good, very helpful

[MathCrazyTutoring]

Yeah, you're absolutely right there. Because of time limitations I used a bit of "magic." Your explanation is useful though, thanks.

[2freet]

Hey,

well done, but do not give the impression, that the 8x is "now" just gone and the following stuff (because we made the 4 out of it?),

put them together... well, ok