Here's the question you clicked on:
berrypicking
I need to solve using matrices. x+2y=9 and x+y=1. I know x=-7 and y=8.
I am not sure how you learnt to solve this by matrix. Have you heard of the Gaussian elimination?
Do you know Cramer's rule?
Write the denominator determinant first. It is the coefficients of the x's and y's. For the x numerator, replace the x coefficients with the constants. For the y numerator, replace the y coefficients with the constants. Then evaluate the determinants.
1 -2 -1 1 is that the denom. deter?
Can you see what I posted?
i got it ended up with {-1 2 {9 1 -1} 1}==={-7,8}