Find $g \circ f$ .
$f ( x ) = x - 9 \quad g ( x ) = x ^ { 2 }$
A) $( g \circ f ) ( x ) = x ^ { 2 } - 18 x + 81$
B) $( g \circ f ) ( x ) = x ^ { 2 } - 81$
C) $( g \circ f ) ( x ) = x ^ { 2 } - 9 x + 81$
D) $( g \circ f ) ( x ) = x ^ { 2 } - 9$
E) $( g \circ f ) ( x ) = x ^ { 2 } + 81$

Question

Find $g \circ f$ . 
$f ( x ) = x - 9 \quad g ( x ) = x ^ { 2 }$  
A) $( g \circ f ) ( x ) = x ^ { 2 } - 18 x + 81$
B) $( g \circ f ) ( x ) = x ^ { 2 } - 81$
C) $( g \circ f ) ( x ) = x ^ { 2 } - 9 x + 81$  
D) $( g \circ f ) ( x ) = x ^ { 2 } - 9$
E) $( g \circ f ) ( x ) = x ^ { 2 } + 81$

Quizplus · Accepted Answer

The composition $g \circ f$ means applying $f$ first and then $g$, so we substitute $f(x) = x - 9$ into $g(x) = x^2$, resulting in $(x - 9)^2 = x^2 - 18x + 81$.

Find g∘fg \circ fg∘f f(x)=x−9g(x)=x2f ( x ) = x - 9 \quad g ( x ) = x ^ { 2 }f(x)=x−9g(x)=x2

Find $g \circ f$ $f ( x ) = x - 9 \quad g ( x ) = x ^ { 2 }$