Find the zeros of the function f (x) = x2+4x-21

Finding the zeros is just factoring the equation. It is also where the parabola crosses the x - axis.

First you need to find two numbers that mutliply to give you - 21 and add to give you 4 then you put it into this form:

(x + 7) (x-3) set each part equal to zero

x+7=0 and x-3=0 you get:

x=-7 and x=3 your zeros

The zeros of the function are x = 3 and x = - 7 to check substitute the zeros into the equation for x and you should get f (x) = 0