Chapter 7 - Polynomial Equations and Factoring - 7.4 - Solving Polynomial Equations in Factored Form - Exercises - Page 381: 22

The x-coordinates are $x=-1$ and $x=-7$.

The graph crosses the x-axis when $y=0$. $\implies y=(x+1)(x+7)=0$ Using zero-product property, we have $(x+1)=0$ or $x+7=0$. Solving for $x$, we obtain $x=-1$ or $x=-7$. The x-coordinates are $x=-1$ and $x=-7$.