#### Answer

x=-5 or -3

#### Work Step by Step

Factor the trinomial.
x$^2$+8x+15=0
(x+5)(x+3)=0
Set each variable factor as equal to zero and then isolate the variable to find the solutions.
x+5=0 or x+3=0
x=-5 or x=-3
Enter the original equation into your graphing utility to observe that the graph crosses the x-axis at -5 and -3.