# Thread: if f(x) = e^2x and g(x) =lnx, then the derivative of...

1. ## if f(x) = e^2x and g(x) =lnx, then the derivative of...

if f(x) = e^2x and g(x) =lnx, then the derivative of y = f(g(x)) at x=e is?

no idea how to do this!

2. Originally Posted by LexiRae
if f(x) = e^2x and g(x) =lnx, then the derivative of y = f(g(x)) at x=e is?

no idea how to do this!
One way of doing it is substituting you get

$f(g(x)) = \exp(2*\ln(x))$

$= \exp(\ln(x^2))$

$= x^2$

Then the derivative

$(f(g(x))' = 2x$

So at x = e

$(f(g(x))' = 2e$

HTH