Finding the Determinant of a 3 x 3 matrix

[jxcxtxl]

oh so its the same thing as cross product. :)

[1adnanhyder]

i love you i am follower of you from 1 year and i am a medical student in 12 level .....and then started graduation in computer sciences but i got huge trouble in maths..:(

then i find you.... love you :)......

my friend helped me alot to learn derivation but :( at last i start studing form you ..and got higher marks form my friend :P just of you thanks my friend god bless you <3

[aelw23]

A million thanks... you're a lifesaver. My prof is a good person, but his handwriting is mysterious, and he has one of the heavier accents I've come across so far...

[patrickJMT]

@aelw23 welcome to college :)

[hom3r]

way better than my university lecturer.

and hes getting paid for teaching.jesus.

[MrOdinakos]

Do you have differential equations, fourier and laplace and laplace convolution?

[rr5001]

is there a faster way to do this for math competitions?

[suspectrom]

hey do u have videos on eigenvalues and eigenvaectors?? Plz give me the link i can't find it ..thnx

[patrickJMT]

@suspectrom not yet

[1977Enter]

Your 7 minute video explained this so much better than my tedious lecturer could in an hour. Thanks!

[lilvic777]

thank youuuuuuuuuuuuuuuuuuuuuuuuuuuu­uuuuuuuuuuuuuuuuuu

[fvnorthwesternfan77]

thank you so much! helps a lot!

[bodyfreakx]

you should become a teacher, seriously. I'm in my first year of IT Engineering and my math teacher explains it way worse than you. Couldn't understand a single thing. Thank you so much for helping me out with my exams. 

[Griesmayer]

Hi patrickJMT,

if I have a 5 x 5 matrix given, for example, I should first do row reduction (lower left triangle should all become zeros) before applying this expansion method, right?

[kpeiman1]

Thanks



[mahanusair]

You ARE AMAZING ! , you have just saved my life !!! my exam is in 2 days , i didn't have any idea about it ! , now everything is just so clear ! :))

[toskala50]

Omg thank u so much. My math teacher can't teach and everything is now clear cause of this video. Thanks do much Patrick! You are amazing

[patrickJMT]

@toskala50 : )

[EvilnessInMe]

I am telling literally every maths student I know about you, you're saving me from my exam! I've been sick for the past week and have found it difficult to revise, so I've been watching your videos for the past week in order to be doing something! I'm now better, my exam's tomorrow and I'm doing examples and getting them right!! Thank you so much!!

[patrickJMT]

@EvilnessInMe glad i could help : ) thanks for spreading the word, the nicest thing you could do for me!

[lionboy55555]

Thank you so much for the help! I definitely feel ready to take on finals now

[BeachBunny12345]

Hi Pat! In an example in my book, to find the determinant, instead of covering up the first row (a11, a12, a13), they cover up the second row (a21, a22, a23). Do you know why?

[LilMizBri1]

Thanks. My algebra teacher didnt explain it clearly but you helped me alot. :)

[ndimhotsi]

u are a star..thank u

[superandy456]

Please can you do a video on eigen vectors and characterstic equations of a (3x3) matrix.

thanks.

BTW my exam is in a week so sooner rather than later would be appretciated. Sorry to be a bit pushy

[patrickJMT]

@superandy456 you are very welcome ; )

[alyraly]

thanks for the effort, very helpful... :)

[Luginess]

this is great but use the shortcuts - so much easier.

[lethalmicky13]

Would you do a find the eigenvectors and eigenvalues of a 3x3 matrix example please :-) great videos.

[FattieAcidProduction]

i have a question that says "deteremine wether or not the set forms a basis for the indicated subspace" {(-4,0,3), (-2,2,3), (-8,4,9)} for R^3 .. i found the det=0 .. so is the answer yes or no... and why??

[FattieAcidProduction]

you went for a11 to a12 to a13 would it be wrong if instead of doing the row i did the column (a11 a21 a31) ???

[JourdinBella1]

iLove you :)

[dragonballzlover9000]

Thank you for making this video. It really helped me because i am applying for whitney young and my teacher said that this kind of problems would be on the entrance exam. I was really worried but now that i have found your videos, every single time i dont understand something i will turn to you. Thank you PatrickJMT

[Karafong]

Thank you naa :) 

[LaidBackSnapBack]

alright how do we know if there is no solution to the matrix.

also lets say A12 (first row second column) is a ZERO, then how do we solve it.

[hjhhkq]

what if the first number is negative?

[beeali23]

Thank You so much :D

[yamahabibi]

thank for this video ,

[polstonj]

thanks, very helpful!

[chakk007]

mr patrick. i was not able to find your videos on youtube regarding eigenvectors or eigen values.. i am unclear about this concept.. what is your suggestion on this 1..

[poyanator]

You make it look so easy... I can't believe I failed a paper1 on this stuff :'(

[Reversification]

Thank you so much, always the best help on youtube

[hvp94]

THANK YOU ! helped a lot!

[gotTammi]

YAY, NOW I CAN FINISH MY HOMEWORK :'D

[MrHav1k]

If I were a woman, I'd marry you

[CaNdaMKD]

Tomorrow I have math exam and this actually helped me sooo 10Q a lot... ooo and my profesor have no idea for math hahaha all the best..

[dramageek1213]

Thanks so much! This was so helpful. Our teacher had us watch this in class when he was absent and it helped so much!

[pinkprincess8910]

THANK YOU!!!!! :)

[patrickJMT]

@pinkprincess8910 very welcome : )

[radiodjcy]

omg yesterday it took me like an hour or even more to understand on how to find the determinant using a cofactor and you have it in like 7 minutes??? mexxx.... anw after this i got to find a video of a row reduction enchelor form or something (for the determinant aswell) i hope you have it mate thanks

[illhvhlda]

can you do the same along the column, not row?

and say you were to do this along the second column.

Should the signs be + , - , and + respectively along the second column?

[matthewdmumford]

Why have I only just seen these videos now!? My exam is tomorrow and you just packed about 3 hours of class work into 7 minutes!!

[patrickJMT]

@matthewdmumford spread the word about the videos, i would appreciate it : )

[Rykersf]

It's a little harder when every term in your matrix is some sinusoidal variation of phi and theta. FINDING THE JACOBIAN ON YOUR OWN IS A PAIN!!! I wish they'd let me use Wolfram on my Calc 3 exams haha.

[Olly999]

Totally honest mate, I did better than my friends on my year 2 MechEng maths homework watching these videos instead of paying attention in class. Incredibly clear, absolutely perfect teaching so thanks very much :D.

[patrickJMT]

@Olly999 congrats on your good grade : ) 

[MisterMD00]

huh, i found a new teacher!

[MrLivetoCompete]

i had to look up this video because my stupid algebra 2 teacher didnt even teach our whole class how to find the determinant of the 3x3 matrix only the 2x2. And apparently half of our assignment deals with the 3x3..

[patrickJMT]

@MrLivetoCompete life is tough

[asianlivelovelaugh97]

test tomorrowww .

i know i'm going to pass now (:

[patrickJMT]

@asianlivelovelaugh97 good luck!!

[RapMusicSucks311]

now why the eff can't my instructor be that clear about this. this was very helpful thank you so much for posting

[pollear]

thanks for sharing i really got to understand 3x3 matrics

[HauptmannRob]

helped me out a lot

[fluflam]

thanks

[evilhafiz4]

Why is the a12 is negative?

[longfenglim]

This is excellent, because my book teaches the determinants as the sum of the entries of a particular i-th row or j-th column multiplied by its corresponding cofactors- and then teaches the cofactors as the determinant of the whole lot times negative one to the power of the i plus j, esentially a circular definition. Thank you very much for it.

[KIETGIANGDBZ]

I'm in honors trig/precalculus and i'm a junior or 11th grader... you are so much better than my teacher.

[jamesvickers19]

I wish my instructors were more like you. Clear, concise, and explanatory. You don't try and make yourself look smarter than your pupils. You just explain the best way to get stuff done. I came to you for Calc II, now for Linear Algebra, and surely many more times. Many thanks

[patrickJMT]

@jamesvickers19 well, teachers and instructors are more educated than their pupils ; ) that is why they are at the front of the room! all the same, glad u like the vids!!

[SamanthaaSays]

@jamesvickers19 ugh exactly teachers always make everything so convoluted.. at least some do

[doobiebotha]

I love you, man.

[Edenio15]

Thank you!! :D

[mitsukai89]

Can anyone tell me the use of a determinant?

[patrickJMT]

@mitsukai89 it tells you if a matrix has an inverse or not, and if certain systems of equations have solutions or not

[patrickJMT]

@mitsukai89 among other things

[fabulapowers]

@mitsukai89 Determinants are also useful in finding the cross product of vectors.  If you don't know what a vector is, it is math concept that has magnitude (length of the vector) and direction, commonly used in physics which represents the acceleration or force acting upon an object. The cross product is just a type of product of two different vectors. It's useful for the physics I'm doing now.

[sizzlecherry26]

omg. thank you so much!!! :)

[frostgirl098]

Thank you so much, I'm trying to test out of Algebra 2 and this helped me so much. :)

[1337greenbagels]

@jcdans You set up the equations like this:

2x - y = -7

x +3y = 0

So you have to set it up in matrix equation form like this:

[2 -1] [x] = [-7]

[1 3] [y] = [0 ] Note:top and bottom of each of those lines go together in 1 matrix.

Then you find the inverse of the 2x2 matrix, and multiply both sides.

The matrix and its inverse cancel out, and the constant side will be your x and y.

I know that wasn't the question you asked, but I hope i figured out what you wanted to do.

[7ood]

Cool video man, i hope you marry britney spears

[mouch30]

thank you for doing my homework <3

[Vidyut444]

your video really helped me.....thanks

keep uploading

[jcdans]

Hey patrickJMT. May i ask something? How can you form a Standard slope form into a Determinant form.

Like this: 2x-y=-7  x+3y=0

[415HolyGuy]

Thanks, Great informative video. Calmly presented in a thorough manner. Much appreciated!

[msbaugh440]

Had to remind myself how to do this for a linear algebra test! thanks for the video you helped a lot!

[AngieStarr85]

You are a savior! I am so happy that I understand the material. I ready for my exam tomorrow!

[tofusauce]

Damn lefties, and their math brain.

[rohanz101]

how do u do 3x3 matrix with simultaneous equations e.g you have 3 equations and need to find the value of all 3 letters.

[s036055]

Thank you kindly :)

[NGViral]

lol Sudoku 

[KyleKairu]

Thank you. This is so much easier to understand than a textbook without visual examples.

[puppydogpretty245]

thank you! plz be my cal teacher!!!

[locoraz1]

OMG thanxxx to you imma get an A tomorro in my college algebra class finally understand it

[virginboy92]

HD allright !! :P

[needmusicnow7]

thanks so much. saved me just in time for exams :D

[tupacsomething69]

why dont you have many matrix vids (eg. eigenvalues, etc)?

[kumar4848]

Any chance you can make a video of finding the determinant of a 4x4 matrix explaining it as u usually do in all your videos...please...

[kakakt]

this video is amazing!!! THANK YOU!!! i struggled with this but now i feel stupid because its so simple. I LOVE YOU.

[dawnie866]

thanks Patrick! are you sure this is the correct way to compute the determinant of an asymmetric matrix? i think it might be only for a symmetric matrix? i have an assignment due in two days and an answer would really help me out.. :) just thought i d try!

[dawnie866]

thanks Patrick! are you sure this is the correct way to compute the determinant of an asymmetric matrix? i think it might be only for a symmetric matrix? i have an assignment due in two days and an answer would really help me out.. :) just thought i d try!

[TheABD101]

can u help me with inverting a 3 x 3 matrix? i'm in grade 8 and our teacher is giving us university level matrices, i get it, but it gets super complicated and then i get stuck. can u pls help?

[hotforgibson]

Your videos are boss man, thanks a lot for making these

[abnalha3mah]

ok but 10_64=_54

[lordfumblesquid]

I learned it differently.

[germzkill]

Whoever dislike this video is an asshole !!!

[Ombaeh]

Assume I try to do this with the second row...The signs would be - + - right? Is there a video where you talk a bit more about signs in determinants?

[VXVANCE]

if you have the matrix ordered from top to bottom as you did, you would have to take a11 times the smaller 2x2, then a21 by the smaller 2x2, then a31 by a smaller 2x2. you went the wrong way assuming that a11,a12, and a13 are all 3 coefficients of the same equation.

[12thando34]

i think this video was helpful in tht it kind of re-taught me what ive learnt in an easier more rememberale way...im definitely passing my upcoming test . thanks

[velutican618]

YOU'RE MARRIED

i would like to be married

[SlimRamjean]

i understood it's coz it comes down to the same thing, whether doing all columns or not and that only the first row makes it quicker

[SlimRamjean]

why did u only take the first row and not the others as well?

other books seem to be showing the same method too :-/

[bhardwajankit42]

sir i really appreciate ur way of teaching ur superb !!

[namie3d]

you're a genius. can i marry you? lol

[Dewzy100]

so only the first row....?

[mworrad213]

Thanks mate

[icouldsmoke2that]

why cant my prof make it this easy to understand!? you have saved me on multiple midterms....

[sweetandsourcandies]

why do you subtract the 2nd term, and then add the 3rd term?

so in your example, you took -6, and +4, why is that?

[kingofgimp]

@sweetandsourcandies

hey sweetandsourcandes... umm i think my response to "eshine65" could help you... the formatting is really bad on youtube comments though :( ... but try copying out on paper what i wrote, in your own style! I really hope it works :D

[TheBustyGamer]

Left handed FTW <3

[eshine65]

Patrick,

If there was a neg in front of the 1 in the matrix that you created, how would that play out in the final answer. I am really confused about the + - + and especially when dealing with matrices with negative numbers. Can you create a matrice with a couple of negative numbers and go step by step because I have been working at this all day and I always bomb out at the end.

[kingofgimp]

@eshine65

I will try to help. The idea is that (in front of each of the 2x2 determinants which patrick breaks the calculation into when searching for the determinant of the 3x3 matrix), he multiplies by the factor he has "covered up" AND by (-1)^(i+j) where i is the row # & j is column # for that covered-up factor. Thus, for first term he has "((-1^(1+1))*1)*det(7,3;9,5)" .. and in the next 2x2 piece he has "(-1*6)*det(2,3;8,5)", where: -1=(-1)^(1+2). Sry for rough formatting. Copy it out!

[pbldiaz28]

You have successfully taught a rocket scientist that fell asleep in class. :D

[bashir26]

Patrick is the MAN!

[ml6008]

Thanks for the video. Believe it or not I am a Diff Eq student who never learned matrices. This is a huge help when computing Wronskians.

[mrfreakengineer]

thx , that was useful and easy to grasp :)

[mymadrid99]

that's really helpful

[videospaz10]

This is called cofactor expansion right?

[zezo7hdk]

is it the same with a 2 x 2 matrix?

[ApplesThatRead]

@zezo7hdk

Nope, in a 2x2 you just multiply the diagonals a x d - b x c when a b are row one and c d are row two.

[absmaninga]

could you make a video on how to solve for the determinants of a 4x4 matrix

[Andreas024]

Thank You very Helpful

[MrDestructorX]

great man!



[avalanch08]

holy shit if i thought of searching for your videos in the beginning of the semester i would not have to bust ass trying to figure this out myself with a shitty teacher....

[Candygobbler]

*Add to faveorites*

Be my math teacher?

[slatz20]

Det isnt 0 so we can solve this system or what?

[evalpeva]

Is that the end? You don't continue with the rest of the columns?

[katey201]

this video is friggin amazing :)

[floyd617]

you are the best.. really helped me out... I LOVE YOU MAN.. no homo :P

[kb192008]

thanks

[dajakesta1234]

hi um may i ask wut is matrix cuz im just a gr 9 kid and i still dont get all the laws

[patrickJMT]

@dajakesta1234 no, you are not allowed to ask.

[dajakesta1234]

@patrickJMT whyyyy

[aba2185]

@patrickJMT hahhaha

[Ph1Lwh0]

@patrickJMT

what a douche.

[nitz47]

@dajakesta1234 lol..a matrix is a way some mathematicians decided to arrange data in rows and columns such that it would be easy to access and manipulate data.

[NawMeegn]

@dajakesta1234 don't stress out over linear algebra you're only in grade 9 you have a long way to go. Enjoy your youth cuz before you know it you're gonna be doing some hard stuff. I.e: this stuff.

[achmed5252]

@dajakesta1234 a matrix is a representation of a system of equations.

[achmed5252]

@dajakesta1234 a matrix is a representation of a system of equations.

[Ghaiyst]

@dajakesta1234 matrix is a lame way to solve a series of equations that only compliactes crap kid. The only way that it seems most directly applicable is in kirchoff's law when you are dealing with circuit problems and that is just a small part of physics. lol

[wullz16]

@dajakesta1234 a rectangular block of numbers, now go and enjoy your childhood!

[eclipse245]

@dajakesta1234 wait 3 years.

[demonscar24]

THANK YOU VERY MUCH SIR THIS VID HAS REALLY HELPED ME A LOT

[GhostofAkina1]

THANKS!!!!!

[knockonwood8]

Thank you!!!

[knockonwood8]

THANKS MR.!!!

[heartachescream]

thank you so much. :)

[patrickJMT]

@heartachescream my pleasure. nice theremin

[jay20112012]

@patrickJMT

thnks u so much ur a legend. I wish my proffessor could teach the way u teach. With ur videos I understand so much more and fear no exams.

keep on the good work

[inneruniverse17]

Could you teach me calculus next semester? Lol.

[patrickJMT]

@inneruniverse17 watch my calculus videos and i will (partly)

[josue215]

I love you man lol but really I wish all my teachers could teach like you...Thanks

[HowBoutDemBoyzz]

or u can do the cross products method

[MandyBedRock]

thank you very much....been trying to grasp this in lecture but it was just too overwhelming, so once again thank you.

[eddieyou1018]

you need to be my algebra 2 teacher

[ariv123456789]

yo yo yo your a boss. enough said

[goalieguy60]

THANK YOU!!!

[emporainator]

i was searching for something else while doing math hw. I am in yr 10 and i did some 6x6 with a tutor ( the 6x6 had algebra too) and this is a very straight forward way of explaining a 3x3 matrix and if you dont mind me asking, but what is your current job

[PanMaggie]

ure amazing!!!! you just help me with my homework. I was on it for past 2 hours and I did not have any idea how to solve it but when I watched your video, my homework seems sooooo simple, and I feel dump about struggling with it;) you are awesome;) thank you so much!!!

greetings from Poland;]