Question

Solve
y=-2 x
y=-9 x+21

Answer 1

X = 3, Y = -6

Explanation:

y = -2x

y = -9x + 21

Bring Y and X on the same side (alone).

0 = -2x – y

-21 = -9x – y

Multiply the top equation by -1 so we can cancel out y later on (to make it easier to solve for x).

0 = 2x + y

-21 = -9x – y

Add the equations.

-21 = -7x

Divide by -7.

X = 3

Solve for Y and check.

Y = -2(3)

Y = -6

Use the other equation to make sure.

(-6) = -9(3) + 21

-6 = -27 + 21

Have a nice day :D