Chapter 8, Problem 4GR

Solution

To find:The value of $y$ when $x=-3$ .

  $y=\frac{48}{7}$ when $x=-3$ .

Given Information:

If $x=7$ when $y=-16$

Calculation:

  $\begin{array}{c}y\propto x\\ y=kx\\ -16=7k\\ -\frac{16}{7}=k\end{array}$

  $k$ is the constant of variation

When $x=-3$ ,

  $\begin{array}{l}y=kx\\ y=\left(-\frac{16}{7}\right)\cdot \left(-3\right)\\ y=\frac{48}{7}\end{array}$

Thus,the value is $y=\frac{48}{7}$ when $x=-3$ and the constant of variation is $-\frac{16}{7}$ .