FP1 (MEI June 07)
The Attempt at a Solution
(i) Find the value of n
I multiplied the top row of A by the left column of B and got the equation:
moved stuff around and ended up with n=21
(ii)Write down the inverse matrix A-1 and write down the conditions on k for this to exist.
Well, I know that k can not be 21 otherwise the determinant will be 0 which cannot be true in this circumstance.
I'm not too sure how to do A-1. I know that the matrix itself must be what B originally was, but I'm not sure how to find out what k is (and thus the determinant).
(iii)Using the result from part (ii), or otherwise, solve the following simultaneous equations.
I solved this using Gaussian elimination. I know how to solve this using the inverse of matrices, but I couldn't quite do part (ii) so i was unable to use that method.