Question

For all values of x, f(x)=3x+k, where k is a constant Given that ff(3) = 7, find the value of k? PLEASE HELP

Answer 1

Not sure if you made a typo here...
if meant F(3) = 7 , then F(3) = 3*3+k = 7 so k equals -2..

Explanation:

If however it meant `ff(3) = f(f(3))`, then:
`f(3) = f(3*3 + k)`,
`=>f(f(3)) = 3(3x+k) + k`
`=> f(f(3)) = 9x + 4k = 7`
`x=3`, therefore `27+4k = 7`
`=> 20 + 4k = 0`
`=> k = -5`

hope this helps....???