Find $( f \circ g ) ( x )$. $f ( x ) = x ^ { 2 } - 4 x \text {, and } g ( x ) = \sqrt { x + 9 }$
A) $( f \circ g ) ( x ) = x + 9 - 4 \sqrt { x + 9 }$
B) $( f \circ g ) ( x ) = \sqrt { x ^ { 2 } - 4 x }$
C) $( f \circ g ) ( x ) = \sqrt { x ^ { 2 } - 4 x } + 9$
D) $( f \circ g ) ( x ) = \left( x ^ { 2 } - 4 x \right) \sqrt { x + 9 }$
E) $( f \circ g ) ( x ) = \sqrt { x ^ { 2 } - 4 x + 9 }$

Question

Quizplus · Accepted Answer

To find $ ( f \circ g ) ( x ) $, we substitute $ g ( x ) $ into $ f ( x ) $:$$( f \circ g ) ( x ) = f ( g ( x ) ) = f ( \sqrt { x + 9 } ) = ( \sqrt { x + 9 } ) ^ { 2 } - 4 ( \sqrt { x + 9 } ) = x + 9 - 4 \sqrt { x + 9 }$$

Find (f∘g)(x)( f \circ g ) ( x )(f∘g)(x) f(x)=x2−4x, and g(x)=x+9f ( x ) = x ^ { 2 } - 4 x \text {, and } g ( x ) = \sqrt { x + 9 }f(x)=x2−4x, and g(x)=x+9​

Find $( f \circ g ) ( x )$ $f ( x ) = x ^ { 2 } - 4 x \text {, and } g ( x ) = \sqrt { x + 9 }$