Question

When solving a quadratic equation by factoring you must set y equal to what value? y=x2 + 3x - 4

Answer 1

x^2 +3x -4 = 0 --> (x +4)(x -1) = 0

Explanation:

Let's find A and B such that

A*B = - 4 and A+B = 3

Numbers are:

A = +4 and B = -1

The factoring equation is y = (x + A)(x + B)

In this specific case: y = (x +4)(x -1)

Solutions to the quadratic equation require

y = (x +4)(x -1) = 0

and hence

x +4 = 0 --> x = -4

x - 1 = 0 --> x= +1