Chapter 9 - Quadratic Functions and Equations - 9-5 Completing the Square - Practice and Problem-Solving Exercises - Page 581: 50

$x \approx 4.8$

$(x+2)(x+1)=40$ $x^2+3x+2=40$ The value of $b$ is 3. The term to add to $x^2+3x$ is $(\frac{3}{2})^2=\frac{9}{4}$ $c=\frac{9}{4}$ Complete the square: $x^2+3x+\frac{9}{4}=40+\frac{1}{4}$ $(x+\frac{3}{2})=\frac{161}{4}$ $x+\frac{3}{2}=6.3$ $x \approx 4.8$