Question

find the zeros of this function y= f(x) (y=zero)
y=(x+2)(x-1) How do I do this!?

Answer 1

You can do this.

If a * b = 0
What do we know about a or b or maybe even both of them?

Answer 2

The zero's are simply -2 and 1

Answer 3

What you need to know is that if the product of two factors is zero, then either one or both of those factors must be a zero.
then either (x+2) = 0 or (x-1)=0, or both then as LagrangeSon has so elequently stated:
x+2=0, then x=-2 and
(x-1)=0, then x=1.