Question

If y=-9 when x = 3, find ywhen x = -5.

Answer 1

y = 15

Step-by-step explanation

We have that y = -9 when x = 3.

To find y when x is -5, we have to use ratio.

We have that the ratio of y to x is:

y : x = -9 : 3 = y : -5

That is:

`\begin{gathered} -9\text{ : 3 = y : -5} \\ \Rightarrow\text{ }(-9)/(3)\text{ = }(y)/(-5) \\ \text{Cross}-\text{multiply:} \\ -9\cdot\text{ -5 = 3 }\cdot\text{ y} \\ y\text{ = }\frac{-9\cdot\text{ -5}}{3} \\ y\text{ = 15} \end{gathered}`

That is the value of y when x is -5.