math (0580) w10 qp22 HELP!!!

[hasman123]

http://www.xtremepapers.me/CIE/Cambridg ... _qp_22.pdf
Q 18) part c....... I dont get it. also what it is an iddentity matrix?

 

[burndtjamb]

The "Identity matrix" is the matrix which will not change any matrix which is multiplied by it. It's a bit like multiplying any number by 1 will get the same number eg. 5 * 1 = 5.

For 2x2 matrices, the identity matrix is (1 0)
------------------------------------- (0 1)

You then just multiple this matrix by 7 and subtract it from matrix A to get the answer.

 

[amaghraby]

a better definition of identity matrix is the matrix resulting if u multiply any matrix by its inverse