# A level maths Core 3 help :)Watch

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Thread starter 2 years ago
#1
Why isn't y = lne^x so dy/dx = 1/e^x correct?
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2 years ago
#2
(Original post by EmLo12)
Why isn't y = lne^x so dy/dx = 1/e^x correct?
ln(e^x) is just x, if I understand correctly?
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2 years ago
#3
y = lne^x is just y = x isn't it? meaning dy/dx would be 1
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2 years ago
#4
(Original post by EmLo12)
Why isn't y = lne^x so dy/dx = 1/e^x correct?
No, you're misquoting the chain rule. Using the chain rule,

Which is what you'd get from recognising that .
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2 years ago
#5
(Original post by EmLo12)
Why isn't y = lne^x so dy/dx = 1/e^x correct?
The chain rule applied to shows that

Applying this to will give you your answer, although simplifying the expression is much easier.
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