Questions: Graphs and Functions
Expressing a function as a composition of two functions
Suppose H(x)=(2x-9)^3.
Find two functions f and g such that (f ∘ g)(x)=H(x).
Neither function can be the identity function.
(There may be more than one correct answer.)
f(x)=
g(x)=
Transcript text: Graphs and Functions
Expressing a function as a composition of two functions
Suppose $H(x)=(2 x-9)^{3}$.
Find two functions $f$ and $g$ such that $(f \circ g)(x)=H(x)$.
Neither function can be the identity function.
(There may be more than one correct answer.)
\[
f(x)=
\]
$\square$
\[
g(x)=
\]
$\square$ $\square$
Solution
Solution Steps
To express \( H(x) = (2x - 9)^3 \) as a composition of two functions \( f \) and \( g \), we need to identify two functions such that \( (f \circ g)(x) = f(g(x)) = H(x) \). One way to do this is to let \( g(x) \) be the inner function and \( f(x) \) be the outer function. For example, we can let \( g(x) = 2x - 9 \) and \( f(x) = x^3 \). This way, \( f(g(x)) = (2x - 9)^3 \).
Step 1: Define the Inner Function \( g(x) \)
To express \( H(x) = (2x - 9)^3 \) as a composition of two functions, we start by defining the inner function \( g(x) \). Let:
\[ g(x) = 2x - 9 \]
Step 2: Define the Outer Function \( f(x) \)
Next, we define the outer function \( f(x) \) such that when \( g(x) \) is substituted into \( f(x) \), we get \( H(x) \). Let:
\[ f(x) = x^3 \]
Step 3: Verify the Composition
To verify that \( (f \circ g)(x) = H(x) \), we substitute \( g(x) \) into \( f(x) \):
\[ (f \circ g)(x) = f(g(x)) = f(2x - 9) = (2x - 9)^3 \]