Question

please help i need help with number 4 and 5

Answer 1

Question 4. Just replace x with 2a.
So f(2a) = 5(2a)^2 + 4(2a)
= 5*4a^2 + 8a
= 20a^2 + 8a

Question 5. Since x = 3, which is more than 1, use the second equation.
f(3) = 3^2 + 1
= 9 + 1
= 10