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NDA 2025 Maths · Mathematics · Derivatives · medium

The derivative of ln x with respect to e^x at x=1 is

Single correct option

The derivative of ln⁡x\ln x with respect to exe^x at x=1x=1 is
  1. A. ee
  2. B. 11
  3. C. 1e\dfrac1e
  4. D. 1e2\dfrac{1}{e^2}
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Answer: (C) 1e\dfrac1e

d(ln⁡x)d(ex)=d(ln⁡x)/dxd(ex)/dx=1/xex\frac{d(\ln x)}{d(e^x)}=\frac{d(\ln x)/dx}{d(e^x)/dx}=\frac{1/x}{e^x}. At x=1x=1 this is 1e\frac1e. The value ee inverts the ratio, 11 is dln⁡xdx\frac{d\ln x}{dx} at 11 alone, and 1e2\frac1{e^2} squares the denominator. Always divide the derivatives, numerator first.
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