Answer: 23+9h+h^2
Step-by-step explanation:
f(3+h)=(3+h)^2+3(3+h)+5=
= 3^2+2*3*h+h^2+3*3+3*h+5=
= 9+6h+h^2+9+3h+5=
= 23+9h+h^2