Question

f(a)= a² + 5 + 2a g(a) = 2a +4 Find (fºg)(a)

Answer 1

$\begin{gathered} f(a)=a^2+5+2a \\ g(a)=2a+4 \end{gathered}$

we must replace g (a) in f (a), so a = g (a)

$\begin{gathered} \mleft(fºg\mright)\mleft(a\mright)=(g(a))^2+5+2(g(a)) \\ (fºg)(a)=(2a+4)^2+5+2(2a+4) \\ (fºg)(a)=4a^2+16a+16+5+4a+8 \\ (fºg)(a)=4a^2+20a+29 \end{gathered}$