Question

Y varies inversely with x if y = 7 when x =-4, find y when x = 5​

Answer 1

y = -
`(28)/(5)`

Explanation:

Given y varies inversely with x then the equation relating them is

y =
`(k)/(x)` ← k is the constant of variation

To find k use the condition y = 7 when x = - 4, then

7 =
`(k)/(-4)` ( multiply both sides by - 4 )

- 28 = k

y =
`(-28)/(x)` ← equation of variation

When x = 5 , then

y =
`(-28)/(5)` = -
`(28)/(5)`