Chapter 5.2, Problem 18PPE

To determine

To determine variation equation that relates $x$ and $y.$

Answer to Problem 18PPE

  $y=-25\times x$

Explanation of Solution

Given:

  $y=125$ when $x=-5$

  $x=12$

Calculation:

Let’s consider the equation as,

  $\Rightarrow y=kx$

Substituting the values of $x$ and $y$ ,

  $\Rightarrow 125=k\times (-5)$

  $\Rightarrow \frac{125}{-5}=k$

  $\Rightarrow k=-25$

So,

  $\Rightarrow y=kx$

  $\Rightarrow y=-25\times x\to (i)$

Now, when the value of $x=12$ ,

Value of $y$ is,

Putting the value $x$ in equation (i),

  $\Rightarrow y=-25\times 12$

  $\Rightarrow y=-300$

Conclusion:

Therefore, the variation equation that relates $x$ and $y$ is $y=-25\times x.$