Question

If f(x) = 5x2 − 4 and g(x) = x − 2, what is (f o g)(-3)?
(A) -129
(B)1
(C)39
(D)121

Answer 1

\[f(g(x))=5(g(x))^2-4=2(x-2)^2-4=2[x^2-4x+4]-4=2x^2-8x+4\]
so fog(-3)=2(-3)^2-8(-3)+4

Answer 2

soo it would be 121

Answer 3

another way and perhaps easy
is to plug -4 into g first
g(-3)=-3-2=-5
then plug -5 into f
f(-5)=?

Answer 4

that's not what i got

Answer 5

what did u get

Answer 6

46

Answer 7

i got it right it was 121

Answer 8

oh i did some mistake in calculations

Answer 9

i got 121 too
just error lol

Answer 10

i used first one
it should read 5x^2-20x+16

Answer 11

i by mistake multiplied by 2 there