Questions: If f(x)=√(x-1) and g(x)=1/(x^2+1) then g[f(x)]=
a) 1/x
b) 1/√(x-1+1)
c) 1/(x-1)
d) -1/√(x^2+1)
Transcript text: If $f(x)=\sqrt{x-1}$ and $g(x)=\frac{1}{x^{2}+1}$ then $g[f(x)]=$
a) $\frac{1}{x}$
b) $\frac{1}{\sqrt{x-1+1}}$
c) $\frac{1}{x-1}$
d) $\frac{-1}{\sqrt{x^{2}+1}}$
Solution
Solution Steps
To find \( g[f(x)] \), we need to substitute \( f(x) \) into \( g(x) \). Given \( f(x) = \sqrt{x-1} \) and \( g(x) = \frac{1}{x^2 + 1} \), we substitute \( \sqrt{x-1} \) into \( g(x) \) to get \( g(\sqrt{x-1}) \).
Step 1: Define the Functions
Given the functions:
\[ f(x) = \sqrt{x - 1} \]
\[ g(x) = \frac{1}{x^2 + 1} \]
Step 2: Substitute \( f(x) \) into \( g(x) \)
We need to find \( g(f(x)) \). Substitute \( f(x) = \sqrt{x - 1} \) into \( g(x) \):
\[ g(f(x)) = g(\sqrt{x - 1}) = \frac{1}{(\sqrt{x - 1})^2 + 1} \]