Recent content by Briane92

Start of with let g of f be a bijection, than state of the definition of a bijection. From there you can prove what must be true of g and f for g of f to meet the definition.

(A^-1) A^2 = (A^-1) ((a+d)A-(ad-bc)I) (A^-1)(A)(A)= " " "" IA = " " "" A= (a+d)I-(ad-bc)A^-1 edit A^-1 = 1/(ad-bc)(a+d)I- 1/(ad-bc)A just check with calculator and it works. Thanks Ray and Ivy.

Thanks for the reply. We did that in class, I have it in my notes. I think the question is asking for something along this lines of A^-1 = (b+a)A-(bc+da)I. That isn't right as I just made it up, but that's the type of equation I think I suppose to come up with from this A^2 =...

1. a) Prove the following holds for A A is a matrix [a b, c d] I is identity matrix. A^2 = (a+d)A-(ad-bc)I. b) Assuming ad-bc not equal to 0, use a) to obtain an expression for A^-1. The Attempt at a Solution I proved the first equation, but I'm not seeing where it relates to...