The zeros of the quadratic function are:
x = -2
x = 3/2
How to find the zeros?
The zeros are the values of x such that f(x) = 0
So we need to solve:
0 = 4x² + 2x - 12
Divide all by 2:
0 = (4x² + 2x - 12)/2
0 = 2x² + x - 6
The solutions are given by:

So the zeros are:
x = (-1 - 7)/4 = -2
x = (-1 + 7)/4 = 3/2