Posted by Travis on .
Use implicit differentiation to find dy/dx. e^4x = sin(x+2y).
This is a practice problem. It says the correct answer is 4e^x/(2sin(x+2y)) but I keep getting 4e^(4x)/(2cos(x+2y)).
I thought the derivative of e^(4x) would be 4e^(4x), not 4e^(x).
And I use chain rule on sin(x+2y) but I get cos(x+2y) * 2dy/dx.
Help would be appreciated, thanks!

Calculus 
Reiny,
e^(4x) = sin(x+2y)
4e^(4x) = cos(x+2y) * (1 + 2 dy/dx)
4e^(4x) = cos(x+2y) + 2 dy/dx cos(x+2y) , I expanded
dy/dx = (4e^(4x)  cos(x+2y) ) / (2cos(x+2y))
looks like the supplied answer is wrong in more than one part.
I also "bolded" that part that you had wrong