### Home > INT2 > Chapter 9 > Lesson 9.4.1 > Problem9-143

9-143.

Complete the square for $y = x^2 + 8x$ to determine the vertex. Then determine the x‑intercepts and make a sketch of the parabola.

Completed square polynomials follow the form $y = x^2 + 2bx + b^2$.
What value of $b$ will create $8x$?

To complete the square, let $b = 4$, so the completed square form would be $y = (x + 4)^2 -16$.
Where will the vertex be? Where will the $x$-intercepts be?