Question

If "u" varies directly with "v", and u = 6 when v = -7, what is "u" when v =4?

Answer 1

u = -
`(24)/(7)`

Explanation:

Given that u varies directly with v then the equation relating them is

u = kv ← k is the constant of variation

To find k use the condition u = 6 when v = - 7, then

6 = - 7k ( divide both sides by - 7 )

-
`(6)/(7)` = k

u = -
`(6)/(7)` v ← equation of variation

When v = 4 , then

u = -
`(6)/(7)` × 4 = -
`(24)/(7)`

Answer 2

u = -24/7

Explanation:

u = 6 = u

v -7 4

-7u = 24

u = -24/7