CHECK MY WORK?
Let f(x) = 4x^2 + x + 1 and g(x) = x2 – 2. Find g(f(x)). Show each step of your work.

f(x)= 4x^2 + x + 1
g(x)= x^2 - 2
g(f(x))= (4x^2 + x + 1)^2 - 2
g(f(x))= 16x^4 + x^2 + 1^2 + 3x^2
g(fx))= 16x^4 + 8x^3 + 9x^2 + 2x - 1

Question

CHECK MY WORK?
Let f(x) = 4x^2 + x + 1 and g(x) = x2 – 2. Find g(f(x)). Show each step of your work.

f(x)= 4x^2 + x + 1
g(x)= x^2 - 2
g(f(x))= (4x^2 + x + 1)^2 - 2
g(f(x))= 16x^4 + x^2 + 1^2 + 3x^2
g(fx))= 16x^4 + 8x^3 + 9x^2 + 2x - 1

anonymous · Answer

@haley15122

tyteen4a03 · Answer

I'm confused; what exactly is line 4 doing?

irishboy123 · Answer

not sure how you did that but FWIW my working gets you to same place....

$g(f(x))= (4x^2 + x + 1)^2 - 2$
ASIDE: $(4x^2 + x + 1)^2  = (4x^2 + (x + 1))^2  $ i don't see this in your solution....?
$= 16x^4 + (2)4x^2(x+1)+ (x+1)^2 -2$
$= 16x^4 + 8x^3 + 8x^2 + x^2 + 2x + 1-2$
$= 16x^4 + 8x^3 + 9x^2 +2x -1$