Find the determinant of a 3x3 matrix using cofactor expansion

[@ritvikrao7389]

This 7 minute video finally made me understand a concept gone over a 50 minute lecture, and 2 hours of struggling to undertsnad a textbook. Thank you.

[@thepianist7379]

The best tutorial on linear algebra I found on YT so far. Much appreciated!

[@junaidrajah5846]

Yeah man simple, easy to understand explanation! great work, thanks.

[@Engineer4Free]

Thanks Junaid!!

[@affinitywealth2938]

Thank you for this. I'm finding it easy to recap on matrices now.

[@yvonneykke]

Took me a few hours but with help of this video it finally makes sense now

[@bhosh]

If you're reading this, there may be some confusion on the signs "alternating". Just putting this out there if anyone needs it. The way it works: + - + - + - + - + For some reason most books / videos choose just the positive ones to explain. Using Row 2 as example (from the video), you get: 24 - 60 + 36 = 0 :) Good Luck!

[@shamineywalsh-dupuis6520]

Thanks, I was wondering about that.

[@sebastianschmidt4493]

Another way is if you add the row and column number together. If its even its + if its odd its -. Example row 3 column 1, 3+1=4 even so its +. Hope this helps

[@austins.219]

So wouldn't it be -24 + 60 - 36?

[@gosiajagusiak6414]

I'm so happy I found your channel!

[@Engineer4Free]

Me too!!! =)

[@sanguin3]

This video is very concise and easy to understand. Thank you for making this!

[@Engineer4Free]

Glad it was helpful!! The full playlist is here: kzbin.info/aero/PL2C8B5877FC12E315

[@lionvstuna4015]

In case the visual method for determining the alternating sign of the co-efficient is confusing, another way to determine the sign is (-1) ^ row + column. For example, F would be (-1) ^ 2 + 3 = -1 ^ 5 = -1.

[@HeavyHockey99]

Good stuff. Thank you

[@zewdiherring9528]

Thank you

[@iiAnbuii]

i'm pretty stupid but I understood this :D Thank you!

[@Engineer4Free]

hahaha don't be too hard on yourself =). If you're looking for some more info on matrices check out videos 35-44 here: engineer4free.com/linear-algebra

[@manikandan-tf9un]

Very helpful! Thanks

[@Engineer4Free]

Glad it was helpful!! =) The full playlist is here too: engineer4free.com/linear-algebra

[@cleo4325]

This was very helpful. Thank you!!

[@Engineer4Free]

Glad to hear it Claudia and thanks for letting me know!

[@malhardegaonkar]

damn bro thanks for the explanation, i was pretty confused here but thank you for clearing my doubts :)

[@tokkia1384]

I love your voice! And great explanation ^^

[@Engineer4Free]

Thanks Tokki!! ^_^

[@tassnem100]

Great 👍🏻 thank you 🌹

[@Engineer4Free]

You’re welcome 😊

[@arashershadi9679]

Thank youuu

[@Engineer4Free]

You’re welcome!!!

[@cassyguy]

At 0:40 you said it always alternates + - + but if I take row 2 isn't it -d| | +e| | -f| |?

[@Engineer4Free]

You start with a positive value for the row or column then alternate. So finding the determinant via cofactors expansion of row 2 would be d|...| - e|...| +f|...|

[@Saronite]

@@Engineer4Free no its -d +e -f ... the formula is ((-1)^i+j) * M(...)

[@stefankarabelov]

@@Saronite you're right

[@samparker5488]

@@Engineer4Free No, it's -, +, -

[@syabongajele6431]

where is the cofactor expansion stated on the caption of the video!

[@johnmoser3594]

If I use the second column, I get the same determinant as if I use the first row, except multiplied by -1.

[@hoangphucpham8044]

Why there is a negative sign in b and f?

[@joshuaraju9630]

because the -/+ of the elements comes down the -1^i+,. so with B it is in row 1and column 2, so i+j=3. and because of this, -1^i+j, here is -1^3, which is -1 :)

[@charityjeffery9511]

Dont use simple terms use some negative as well 😢

[@learner6656]

wow how do you write that fast

[@arielhilmifuadi8173]

Bro 7 minute equal my lecture 50 minute

[@TawfikAlsane]

You did not explain the cofactor at all

[@liammack4592]

I don't see you determine a coefactor matrix what-so-ever....