Question

Evaluate (gf)(8) given that f(x)=sq root of x+17 and g(x)=x^2-43
(gf)(8)=?

Answer 1

g(f(8))
g(sqrt{25})
g(5)
5^2 - 43
25 - 43
g(f(8)) = -18

Answer 2

thank you!

Answer 3

No problem, compositions of functions gave me trouble too.

Answer 4

is this composition or multiplication?

Answer 5

\[f(x)=\sqrt{x+17}\]\[g(x)=x^2-43\]\[g(f(x))=(\sqrt{x+17})^2-43=x+17-43=x-26\]\[(8)-26=-18\]

Answer 6

Composition, f(g(x))

Answer 7

\[fg(x)\] or
\[f\circ g(x)\]?

Answer 8

oh ok you have the answer then.

Answer 9

\[f(8)=\sqrt{8+17}=\sqrt{25}=5\]
\[g(5)=5^2-43=25-43=-8\]

Answer 10

25 - 43 = -18, not -8

Answer 11

One tip, in g(x), replace every "x" term with f(x)