If f : R → R is defined by f(x) = 3x + 2, find f (f (x)).
Question:

If $f: R \rightarrow R$ is defined by $f(x)=3 x+2$, find $f(f(x))$.

Solution:

$f(f(x))=f(3 x+2)$

$=3(3 x+2)+2$

$=9 x+6+2$

$=9 x+8$