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Ifthen show thatIf y=logx+logx+logx+...∞,then show that dydx=1x(2y-1).

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Question

`"If"  y = sqrt(logx + sqrt(log x + sqrt(log x + ... ∞))), "then show that"  dy/dx = (1)/(x(2y - 1).`

Sum
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Solution

`y = sqrt(logx + sqrt(log x + sqrt(log x + ... ∞)))`

∴ `y^2 = log x + sqrt(log x + sqrt(log x + ... ∞)`

∴ y2 = log x + y

Differentiating both sides w.r.t. x, we get,

`2y. dy/dx = (1)/x + dy/dx`

∴ `(2y - 1) dy/dx = (1)/x`

∴ `dy/dx = (1)/(x(2y - 1)`.

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Chapter 1: Differentiation - Exercise 1.3 [Page 40]

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