Question

how do I find the x-intercepts for y=x^2+8x+15

Answer 1

Set y = 0 and factor/solve for x.

Answer 2

\(\large y=x^2+8x+15\implies 0=x^2+8x+15 \quad
\begin{array}{cccllll}
0=x^2&+8x&+15\\
&\uparrow &\uparrow \\
&5+3&5\cdot 3
\end{array}\)