Question

y varies directly as the square of R. If y is 7 when R is 3​, find y when R is 15 . ​a) Write the variation. ​b) Find y when R is 15.

Answer 1

Explanation:

a.

`y = k {r}^(2)`

`7 = k {3}^(2)`

`7 = 9k`

`k \: = (7)/(9)`

`y \: = (7)/(9) {r}^(2)`

b.

`y \: = (7)/(9) * {15}^(2)`

`y = (7)/(9) * 225`

y = 175