Inverses using determinants

Finding the inverse of A using determinants, and showing how to get the formula for a 2x2 inverse. It’s a cofactor extravaganza
Note: The matrix you get on the numerator is called the adjugate of A, adj(A)
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Check out my Determinants playlist: • Determinants

[@SlipperyTeeth]

I love this method for the 3×3, because 2×2 determinants are so easy to calculate. You basically just go along each entry and write down its value.

[@noname_whatsoever]

Awesome as always! Please keep the linear algebra streak going!

[@japotillor]

This is actually my preferred way to find a 3x3 inverse. Its been a while, but I think you can use row reduction to derive the formula...I miss doing these problems.

[@drpeyam]

Easier: You can use Cramer’s rule to derive that formula

[@japotillor]

That's true, it must be morning since my first thought was row reduction Cramer's Rule is way easier

[@justinfisher5339]

wow you are a great teacher!

[@shandyverdyo7688]

Please make a videos about left inverse and right inverse for *non square matrix* It's few of youtuber who want to talk bout it. And i hope u share your knowledge to me Dr. 😍

[@drpeyam]

I made a video on why nonsquare matrices are not invertible!

[@shandyverdyo7688]

@@drpeyam yeah but sometimes. It might be have left or right inverse dr. Hmmm. But i don't remember where i can found this on.

[@drpeyam]

Yeah, I think the way you would do it is just you row-reduce until you get a rectangular identity matrix, and you write the row-reductions as elementary matrices (I think that’s how you do it, not 100% sure)

[@shashwat4920]

Dr peyam!!!!

[@brianlamptey4823]

Would it be possible for you to explain the solution of Putnam 2018 question A2?

[@vijayank1170]

Dr. Peyam this is the standard method taught in Indian high schools.. Inverse = Adjoint /determinant

[@drpeyam]

Hmmm, seems inefficient though, row-reduction is much better!

[@vijayank1170]

@@drpeyam Dr peyam Can you make a video explaining the concepts of pointwise and uniform convergence please..

[@drpeyam]

There’s a video on covering compactness and uniform continuity, that should explain it

[@vijayank1170]

@@drpeyam it's so nice of you replying to all the comments.. Anyway I'll check the video.. Thanks Dr peyam

[@newtonnewtonnewton1587]

It is nice D peyam i observe that most of your lectures are a bout algebra & matrix i hope u talking a bout calculus ? U r wonderful

[@drpeyam]

There’s a calculus playlist :) I’m on a linear algebra streak, but I’ll add some calculus videos now and then!

[@newtonnewtonnewton1587]

@@drpeyam thanks alot D peyam

[@wilhellmllw3608]

Does that work on nXn or just with 2 and 3?

[@drpeyam]

Also works on nxn

[@wilhellmllw3608]

@@drpeyam thank you! Just saw the demonstration on your other video about it!

[@shivimish9962]

I don't know why but we call the adjugate matrix the adjoint matrix. It's better to have common terminology. 😀

[@MrQwefty]

1:32 2 plus 2 is 4 minus 3 that's 1 quick maths