Question

If x varies inversely with y and x = 4 when y = 9, find x when y = 6.

Answer 1

x = 6

given x varies inversely with y then

xy = k ← k is the constant of variation

to find k use the condition x = 4 when y = 9, hence

k = 4 × 9 = 36

x =
`(36)/(y)` ← inverse variation equation

when y = 6, then x =
`(36)/(6)` = 6