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If f(x) = log x2, where x > 1 find derivative of f(x)
1. \(\rm \frac{2}{x^2}\)
2. \(\rm \frac{1}{x}\)
3. \(\rm \frac{2}{x}\)
4. \(\rm \frac{1}{x^2}\)

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Correct Answer - Option 3 : \(\rm \frac{2}{x}\)


Chain rule: \(\rm \frac{d}{dx}[f(g(x))]= f'(g(x)) g'(x)\)

If y = log x, then f'(x) = 1/x

And if y = xn, then f'(x) = nxn - 1


f(x) = log x2, x > 1

Differentiating with respect to x, we get

⇒ f'(x) = (\(\rm \frac{1}{x^2}\))\(\rm \frac{d x^2}{dx}\) 

⇒ f'(x) = \(\rm \frac{2x}{x^2}\)

⇒ f'(x) = \(\rm \frac{2}{x}\)

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