00:01
This problem, we're given the system of equation is x plus y equals minus one, and x minus y equals minus nine.
00:07
Our goal is to solve from both x and y through the use of kramer's rule, which involves using matrices.
00:14
So according to kramer's rule, we need to find the determinant of three different matrices.
00:21
Determinate d equals the determinant of the matrix from the coefficients of x and y.
00:30
So the first equation now will be 1x and 1 y, and 1x and minus 1y, like that.
00:41
The determinant d x is the same thing as d, except the first column will be replaced by coefficients in the answer column here, minus 1 and minus 9.
00:59
You can minus 1 and minus 9 in the first column, and we keep the second column as is, so 1 minus 1.
01:06
And then in green, the determinant d of y is the determinant of d, except the answer column now replaces the second column in the matrix.
01:17
So the answer column would be minus 1 and minus 9 in the second column, with the first column intact of 1 and 1.
01:25
So it's fine these three determinants.
01:30
So d equals 1 times minus 1, right? minus 1 times 1...