00:01
Okay, so our goal here is to find the unknown matrix a when we know that a times some matrix equals an output matrix.
00:10
In order to do that, we're going to have to take its inverse because this equation is of the form ax equals b.
00:17
Except instead of solving for x like we usually do, we're solving it for a.
00:23
So if we multiply both sides by the inverse of x, we'll get a times x times the inverse of x equals b times the inverse of x, which simplifies to a equals b times the inverse of x.
00:40
Now to find the inverse of x, we use this equation, which i've already written out.
00:45
So we simply plug in our values for the matrix x.
00:50
Let me get 0, 1, 2, negative 1, to the negative first power equals 1 over a times d, which is 0 times negative 1, which is just 0, minus 1 times 2, which is just 2, which is just 2.
01:17
Then we input our values we want d here so this is going to be negative 1 here is negative b which is negative 1 in place of c we use negative c which is negative 2 0 and this simplifies to negative 1 half times the equation negative 1 i said equation instead of matrix so we can distribute that negative 1 half that's going to make our inverse matrix one half one half one zero now we have to multiply this equation by our output equation and remember here it's b times x to the negative first power because matrix multiplication is not commutative so the b has to be the first equation...