00:01
In this problem, we want to start by calculating the inverse matrix of a.
00:05
So we have a formula to compute this.
00:07
First we're going to want to find the determinant of our matrix.
00:11
So that means that we're going to start by multiplying across this diagonal.
00:15
So we'll multiply 7 by 2 to get positive 14.
00:18
And then we're going to subtract the result of multiplying along our other diagonal.
00:22
So minus 12.
00:24
And we get a determinant of 2.
00:26
So from here, we're going to go ahead and find the reciprocal.
00:30
Of this determinant, which is one half, and we're going to perform a scalar multiplication along our initial matrix a with a few modifications.
00:42
So our first diagonal, seven and two, we're just going to switch those two numbers.
00:46
So instead of seven in the top left and two in the bottom right, we now have two in the top left and seven in the bottom right.
00:53
And along our other two diagonals, we're just going to multiply by negative one.
00:57
So instead of having four in the top right, we now have negative four...