Question

Evaluate the function for x = 3a. f(x)=2x^2-3x+4

Answer 1

assuming you mean for x=3
f(3)=2(3)^2-3(3)+4
f(3)=2(9)-9+4
f(3)=18-5
f(3)=13

it is 13

Answer 2

To evaluate the function for x = 3a, substitute the 3a to the all the x's of the function. Such that,
f(3a) = 2(3a)² - 3(3a) + 4
Simplifying to obtain the final answer,
f(3a) = 18a² - 9a + 4