Question

Solve the system using the linear combination method.

first equation. 5 x plus y equals 5 second equation. 10 x plus 3 y equals 20

Answer 1

C: 1, -5

Hope this helps!

Explanation:

The x-coefficients have a nice ratio, and one of them is negative. That makes it easy to eliminate x by multiplying the first equation by 4 and adding the second equation:

4(5x+3y) +(-20x-7y) = 4(-10) +(15)

5y = -25 . . . . . simplify

y = -5 . . . . . . . divide by 5

Substitute this result into either equation to find x. I choose to use the first equation.

5x +3(-5) = -10

5x = 5 . . . . . . add 15

x = 1 . . . . . . . divide by 5

The solution is (x, y) = (1, -5).