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Question: Answered & Verified by Expert
If \(f(x)=\frac{x}{\sqrt{1+x^2}}\), then (fof of \()(x)\) is
MathematicsTrigonometric EquationsBITSATBITSAT 2010
Options:
  • A \(\frac{3 x}{\sqrt{1+x^2}}\)
  • B \(\frac{\mathrm{x}}{\sqrt{1+3 \mathrm{x}^2}}\)
  • C \(\frac{3 x}{\sqrt{1-x^2}}\)
  • D None of these
Solution:
2382 Upvotes Verified Answer
The correct answer is: \(\frac{\mathrm{x}}{\sqrt{1+3 \mathrm{x}^2}}\)
\(\mathrm{f}(\mathrm{x})=\frac{\mathrm{x}}{\sqrt{1+\mathrm{x}^2}}\)
\((f o f)(x)=\frac{\frac{x}{\sqrt{1+x^2}}}{\sqrt{1+\frac{x^2}{1+x^2}}}=\frac{x}{\sqrt{2 x^2+1}}\)
\((fofof)(x)=\frac{\frac{x}{\sqrt{2 x^2+1}}}{\sqrt{1+\frac{x^2}{2 x^2+1}}}=\frac{x}{\sqrt{1+3 x^2}}\)

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