Answer:
3 , -5
Step-by-step explanation:
hello :
f(x)=x²+2x-15
compliting squard : f(x)=(x²+2x+1) - 1-15
f(x) = (x+1)²-16
f(x) = 0 means : (x+1)²-4² =0
by identity : a²-b² =(a-b)(a+b).......a=x+1 and b= 4
(x+1-4)(x+1+4) = 0
(x-3)(x+5)=0
x-3=0 or x+5=0 so : x=3 or x= -5
the zeros of the function f(x)=x^2+2x-15 are : 3 , -5
