Question

How do you solve the following system of equations by eliminating the y-values? I've already solved it by eliminating the x-values so I know the answer is (-9/2, -10) but I'm having trouble getting that answer by eliminating the y-values.


`2x-3y=21\\-6x+2y=7`

Answer 1

Explanation:

The coefficients of the y terms are -3 and 2. The least common multiple of 3 and 2 is 6. So multiply the first equation by 2 and the second equation by 3, so that the y terms have a coefficient of 6.

4x − 6y = 42

-18x + 6y = 21

The signs are opposite, so add the equations together.

-14x = 63

x = -9/2