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When the tangent to the curve y = x log x is parallel to the chord joining the points (1, 0) and (e, e), the value of x is ______. - Mathematics

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Question

When the tangent to the curve y = x log x is parallel to the chord joining the points (1, 0) and (e, e), the value of x is ______.

Options

  • `e^(1/(1−e))`

  •  `e^((e−1)(2e−1))`

  • \[e^\frac{2e - 1}{e - 1}\]

  • \[\frac{e - 1}{e}\]

MCQ
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Solution

When the tangent to the curve y = x log x is parallel to the chord joining the points (1, 0) and (e, e), the value of x is `bb(e^(1/(1−e)))`.

Explanation:

Given: \[y = f\left( x \right) = x\log x\]

Differentiating the given function with respect to x, we get

\[f'\left( x \right) = 1 + \log x\]

\[\Rightarrow\] Slope of the tangent to the curve = \[1 + \log x\]

Also,

Slope of the chord joining the points 

\[\left( 1, 0 \right) \text { and  } \left( e, e \right)\] (m) = \[\frac{e}{e - 1}\]

The tangent to the curve is parallel to the chord joining the points \[\left( 1, 0 \right) \text { and } \left( e, e \right)\].

\[\therefore m = 1 + \log x\]

\[\Rightarrow \frac{e}{e - 1} = 1 + \log x\]

\[\Rightarrow \frac{e}{e - 1} - 1 = \log x\]

\[ \Rightarrow \frac{e - e + 1}{e - 1} = \log x\]

\[ \Rightarrow \frac{1}{e - 1} = \log x\]

\[ \Rightarrow x = e^\frac{1}{e - 1}\]

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Chapter 15: Mean Value Theorems - Exercise 15.4 [Page 20]

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RD Sharma Mathematics [English] Class 12
Chapter 15 Mean Value Theorems
Exercise 15.4 | Q 7 | Page 20

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