First subtract 7 from each side of the equation.
4x^2 - 12x - 7 = 0.
Now we can substitute terms into our friend the quadratic equation, which you should memorize. Or we can try a few simple factors. 7 is prime, so to make -7 one number must be positive and one must be negative.
The first pair I tried, (2x + 1)(2x - 7) yield a middle term of -12x. Therefore, setting each to zero yields: x = -1/2, or x = 7/2.
