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If ex + ey = ex+y , prove that ddedydx=-ey-x - Mathematics

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Question

If ex + ey = ex+y , prove that `("d"y)/("d"x) = -"e"^(y - x)`

Sum
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Solution

Given that ex + ey = ex+y.

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

`"e"^x + "e"^y ("d"y)/("d"x) = "e"^(x + y) (1 + ("d"y)/("d"x))`

or `("e"^y - "e"^(x + y)) ("d"y)/("d"x) = "e"^(x + y) - "e"^x`

Which implies that `("d"y)/("d"x) = ("e"^(x + y) - "e"^x)/("e"^y - "e"^(x + y))`

= `("e"^x + "e"^y - "e"^x)/("e"^y - "e"^x - "e"^y)`

= –ey–x.

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Chapter 5: Continuity And Differentiability - Solved Examples [Page 94]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 5 Continuity And Differentiability
Solved Examples | Q 9 | Page 94

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