1. (3x2 + 4x - 12) = (x + 5)

Divide using synthetic division

If you are solving for x then here's how:

(3x2 + 4x - 12) = (x + 5)

Remove the x on the left by remove one x from both of the sides.

(3x2 + 3x - 12) = 5

Add 12 onto both sides

(3x2 + 3x) = 17

Multiply

(6 + 3x) = 17

Take away 6 from both sides

3x = 11

Divide by 3 on both sides

x = 3.666 recurring