Question

Find the constant of proportionality, then write an equation relating x and yy is directly proportional to x, and y = 81 when x = 9

Answer 1

When x=9, y=81.

To find the proportionality constant take the ratio of y/x.

`\begin{gathered} (y)/(x)=(81)/(9) \\ =9 \end{gathered}`

Thus, the proportionality constant is 9.

The relation between y and x can be determined as,

`\begin{gathered} (y)/(x)=constant \\ (y)/(x)=9 \\ y=9x \end{gathered}`

Thus, the required relationship between x and y is y=9x.