## Intermediate Algebra for College Students (7th Edition)

Hence, by using the formula college students spend in $2011$ is $\$ 89.6$. which is overestimates by$ \$2.6$ billion.
From the question we have $D(x)=1.2x^2+1.6(x+40)$, Where, $D$ is discretionary spending in billions of dollars and $x$ is years after $2007$. Therefore, the value of $x$ for the year $2011$ is $=2011-2007 =4$. plug in $x=4$ into the formula. $D(4)=1.2(4)^2+1.6(4+40)$. Clear the parentheses. $D(4)=1.2\times 16+6.4+64$. Simplify. $D(4)=89.6$. By observing the graph the value of $D(4)$ is $87$ billions of dollars. Hence, the model overestimates the actual value by $87-89.6=-2.6$ billions of dollars.