What are the zeros of this function?

f(x) = (x + 4)2 – 9

Set the function equal to zero and solve for x. 
x=1/2

Those are the values of x that make f(x)=0
so

0=(x+4)²-9
add 9 to both sides
9=(x+4)²
sqrt both sides
remember to get positive and negative roots
+/-3=x+4
minus 4 both sides
+/-3-4=x
3-4=x or -3-4=x
-1=x or -7=x

the zeros occur at (-1,0) and at (-7,0)