# Geometric matrix problem!

#### LaraCroft

1. Homework Statement

If A =

[ -4e^4t sin(9t) -4e^5t cos (9t) ]
[ 4e^4t cos (9t) -4te^5t sin (9t) ]

then A^-1 =

[ ___ ___ ]
[ ___ ___ ]

2. Homework Equations

how do you deal with the exponents?

3. The Attempt at a Solution
Put into RREF, and then see what the inverse is?

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#### badphysicist

Well, you know that a matrix times its inverse gives the identity matrix. Set up the inverse matrix as having four unknown numbers in it (a,b,c,d for instance) and plug it into the equation I just mentioned. This will give you some equations to solve to find the parts of the inverse matrix.

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