Find a if f(2)=16

Question

F(x) =2x³-ax²-3.

Answer 1

Since f(x) = 2x³ - ax² - 3, we begin by plugging 2 in every where there's an x.

This gives f(x) = 2(2)³ - a(2)² - 3

Then, we know this equation will equal 16 because f(2) = 16 so:

16 = 2(2)³ - a(2)² - 3

16 = 2(8) - a(4) - 3

16 = 16 - 4a - 3

16 = -4a - 19

-3 = -4a

a = 3/4