Question

Find the zeros of y = 4x2 – 12x – 16

Answer 1

x=-1 or x=4

Explanation:

First divide by 4 to get rid of the factor 4 at x², then you have:

x² - 3x - 4 = 0

to factor that, look for two numbers that when added, give -3, and when multiplied, give -4. This is guesswork but usually doable:

-4 + 1 = -3

-4 * 1 = -4

so -4 and +1 are our numbers.

The factorization is therefore: (x - 4)(x + 1) = 0, and the solutions are

x-4 = 0 or x+1 = 0, so x=4 or x=-1