Question

Suppose y varies inversely with x, how do you write an equation for the inverse variation if y = 9 when x = 4?

Answer 1

If `y` varies inversely with `x`
then
`y = c/x` for some constant `c`

Given that `(x,y) = (4,9)` is a solution to this equation:
`9 = c/4`

`rarr c= 36`

and the equation is
`y = 36/x`