Question

If `f(x)=3x+4` and `g(x)=x^2-1`, how do you find `f(g(a))`?

Answer 1

`f(g(a))=3a^2+1`

Explanation:

Evaluate the 'inner' function first. That is g(a)

`"To evaluate g(a) substitute x= a into g(x)"`

`rArrg(color(blue)(a))=color(blue)(a)^2-1`

`"To evaluate f(g(a))substitute " x=a^2-1 " into "f(x)"`

`rArrf(g(a))=f(color(red)(a^2-1))=3(color(red)(a^2-1))+4`

`rArrf(g(a))=3a^2-3+4=3a^2+1`