Question

If f (2) = 60 – 5.
find x for f (x) = 13

Answer 1

The required value of
`x` is
`(3)/(5)`

Explanation:

Given,

f (2) = 60 – 5

= (30 X 2) - 5

∴ f (x) =
`30x-5`

Again,

f (x) = 13 [given]

`30x-5=13\\or, 30x= 13+5\\or, 30x=18\\or, x=(18)/(30) \\\\or, x=(3)/(5) \\`

∴
`x=(3)/(5)`

Verification:

f (x) =
`30x-5`

∴ f (
`(3)/(5)`) = (30 X
`(3)/(5)`) - 5

= 18 - 5

= 13

∴ The required value of
`x` is
`(3)/(5)`