Question

If y varies directly ás x, and y = 7 when x = 3. find y when x=7

Answer 1

y =
`(49)/(3)`

Explanation:

Given y varies directly as x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition

x = 3 when y = 7

k =
`(y)/(x)` =
`(7)/(3)`, thus

y =
`(7)/(3)` x ← equation of variation

When x = 7, then

y =
`(7)/(3)` × 7 =
`(49)/(3)`