Chapter A.6, Problem 9AYU

To determine

To fill: To complete the square of the expression $x^2 - 9x$, you would _____ the number _____.

Answer to Problem 9AYU

Add, $\frac{81}{4}$.

Explanation of Solution

To complete the square of the expression $x^2 - 9x$, you would add the number $\frac{81}{4}$. Since

$x^2-9x+{\left(\frac{1}{2}.9\right)}^2=x^2-\frac{1}{2}x+\frac{81}{4}={\left(x-\frac{9}{2}\right)}^2$.