Question

What is the value of f ( − 3a ), if f ( x ) = 2x 2 + 6x ?

Select one: a. 18a 2 - 9a
b. 18a 2 - 18a
c. 9a 2 - 18a
d. 18a - 6a

Answer 1

b. 18a² - 18a

Explanation:

`f(x)=2x^2+6x\\\\f(-3a)\to\text{substitute}\ x=-3a\ \text{into}\ f(x):\\\\f(-3a)=2(-3a)^2+6(-3a)=2(-3)^2a^2-18a=2(9)a^2-18a=18a^2-18a`