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KCET · Maths · Differentiation

If \(y=\left(1+x^2\right) \tan ^{-1} x-x\), then \(\frac{d y}{d x}\) is

  1. A \(2 x \tan ^{-1} x\)
  2. B \(\frac{\tan ^{-1} x}{x}\)
  3. C \(x^2 \tan ^{-1} x\)
  4. D \(x \tan ^{-1} x\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(2 x \tan ^{-1} x\)

Step-by-step Solution

Detailed explanation

Given,
\[
y=\left(1+x^2\right) \tan ^{-1} x-x
\]
Differentiating the given function w.r.t. \(x\)
\[
\begin{aligned}
\frac{d y}{d x} & =\left(1+x^2\right) \frac{d}{d x}\left(\tan ^{-1} x\right)+\tan ^{-1} x \frac{d}{d x}\left(1+x^2\right)-\frac{d}{d x}(x) \\
& =\left(1+x^2\right) \frac{1}{\left(1+x^2\right)}+\tan ^{-1} x(2 x)-1 \\
& =1+2 x \tan ^{-1} x-1=2 x \tan ^{-1} x
\end{aligned}
\]