Help needed for calculating Adjoint of a Matrix, Please help me.?

Question

Hii guys can you give me trick to calculate the Adjoint of a matrix ; especially of order 3 X 3.

Its ok when it comes to calculate the adjoint of a matrix of order 2 as we just have to switch a11 & a22 elements & change the sign of a12 & a21 elements. But when it comes to find the adjoint of a matrix of order 3 X 3 then it gets really messy & time taking due to which it can be hazardous in exams as I will be having limited time on every question in order to finish all questions successfully.

When it comes to find the adjoint of a matrix of order 3 X 3 or more then we have to first find the Minor of the matrix, then the Co-factor of that matrix & then we get adjoint of matrix after transposing the co-factor, so in this way it gets really messy & time taking & it has a high probability of mistake.

SO PLEASE SUGGEST A MTHOD OR TRICK SO THAT I CAN FIND THE ADJOINT OF A MATRIX OF ORDER 3 X 3 OR MORE WITH EASE.

THANKS EVERYONE.

Answer 1

Well having the same problem mate..I am also searching any method or trick. Well what I have found out so far is that when you take out cofactors then you have to write it & then transpose it to get adjoint..well you can delete that step by directly writing the adjoint..after getting the cofactors..they trick is that just write elements like a11, a12, a13...one below each other when you're writing the adjoint!

Answer 2

There is no trick that I know of. You just have to be very careful. It is important to get the sign of the mino right. These questions tend to be a bit of mathematical punishment.

Answer 3

If you go through this tutorial carefully, it explains it all.