Find the values of x

Question

X² = -4y

y = 3x + 5

Answer 1

y = -x²/4

Substitute into bottom equation

-x²/4 = 3x + 5

Multiply both sides by 4

-x² = 12x + 20

Add x² to the other side

x² + 12x + 20 = 0

Use the quadratic formula or simplify with parentheses

(x+10) (x+2) = 0

Answer: x = -10, -2