Question

Please help me
Let f(x)=x^2+5 and g(x)= (x+5)/5 . find (g o f)(-3).

Answer 1

`f(x) = x^(2) + 5`
`g(x) = (x + 5)/(5)`

First find gf(x) by substituting the expression for f(x) wherever there is an x in the g(x) function


`gf(x) = (( x^(2) + 5 ) + 5)/(5)`

Simplify the equation and then substitute -3 where the x's are in gf(x)

gf(x) =
`( x^(2) + 10)/(5)`

gf(-3) =
`((-3)^(2) + 10 )/(5)`

=
`(9 + 10)/(5)`

=
`(19)/(5)`

Keen to note that if you worked f(-3) first and then substituted that into g(x) then you would get the same answer.