Derivative of a function, Is my answer correct?

[neutron star]

Homework Statement

y=e^9Θsin(8Θ)

Homework Equations

The Attempt at a Solution

dy/dΘ=e^9Θ(sin(8Θ)+8cos(8Θ))

 

[Bohrok]

[Edit] I didn't catch the missing 9; sorry about that.

 

[lanedance]

is that (using t for theta)

y=e^(9t.sin(8t)) or y=(e^(9t)).sin(8t)?

 

[neutron star]

Ugh, it said incorrect...

 

[lanedance]

if it is
y=(e^(9t)).sin(8t)

i think you should get an extra factor of 9
y'=(e^(9t)).(9sin(8t)+ 8cos(8t))

 

[Pengwuino]

Lanedance is right, you get that factor of 9 when taking the exponential derivative.