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If xm . yn = (x + y)m+n, prove that dydxd2ydx2 = 0

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Question

If xm . yn = (x + y)m+n, prove that `("d"^2"y")/("dx"^2)` = 0

Sum
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Solution

Given that: `"dy"/"dx" = y/x`

Differentiating both sides w.r.t. x

`"d"/"dx"("dy"/"dx") = "d"/"dx"(y/x)`

⇒ `("d"^2y)/("dx"^2) = (x* "dy"/"dx" y*1)/x^2`

= `(x * y/x - 1)/x^2`   .....`[because "dy"/"dx" = y/x]`

= `(y - y)/x^2`

= `0/x^2`

= 0

Hence, `("d"^2y)/("dx"^2)` = 0.

Hence proved.

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Chapter 5: Continuity And Differentiability - Exercise [Page 113]

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NCERT Exemplar Mathematics Exemplar [English] Class 12
Chapter 5 Continuity And Differentiability
Exercise | Q 80. (ii) | Page 113

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