What is the solution of the system ? Solve using matrices

Question

{ x + 2y = 9

{ x + y = 1

Answer 1

Answer 2

System is | 1 2 | | x | = | 9 |

| 1 1 | | y | |1 |

You can solve this by Gaussian elimination, by inverting the matrix and multiplying the inverse times the constant vector, or you could use Cramer's rule.

It's a pain to draw the matrices repeatedly so I'll describe the steps to G-E

Subtract row 1 from row 2: you get 0 -1 in the 2nd row and constant vector 2nd row is -8

Now multiply 2nd row by -1: 0 1 8

Now subtract 2 x 2nd row from 1st row so that final result is

| 1 0 | | x | = | -7 |

| 0 1 | | y | | 8 |