f(x)= x^4-3e^x(cos(x))+e^6?

Question

I tried every single way but for some reason could not get the right answer. Here is what i did: i used product rule for the middle term and ended up getting an equation which looks right but is not. teh equation i got after solving is 4x^3+3e^x*sin(x)+e^6

Answer 1

Are you trying to find the derivative of F(x)? If so, then
F'(x) = 4x^3 +3e^xsin(x) -3e^xcosx
f'(x) = 4x^3 + 3e^x( sinx-cosx)

Answer 2

Be careful,

(1) e^6 is a constant, it's derivative is zero.

(2) Use the product rule to differentiate e^x ( cos(x) ).

Good Luck!!