Answer:
Step-by-step explanation:
12² + 4x = 0
144 + 4x = 0
subtract 144 from both sides
144 + 4x - 144 = 0 - 144
4x = -144
divide both sides by 4
[tex]\frac{4x}{4}=\frac{-144}{4}\\\\x=-36[/tex]