- #1
Schrodinger's Dog
- 835
- 7
Homework Statement
Have to use the product rule twice.
[tex]\frac{d}{dx}=x^4e^xsin(x)[/itex]
I got about as far as the first use of the product rule then stalled when I had to use it again.
got this:-
[tex](1+x^2)sin(x)+(x^4e^x)sin(x)[/tex]
but not this:-
[tex](4x^3e^x+x^4e^x)sin(x)+x^4e^xcos(x)[/tex]
Problem is the books explanation misses out the first step and proceeds to the second order differential and the answer.
[tex]x^3e^x((4+x)sin(x)+xcos(x))[/tex]
Can't work out how to get there, any pointers? Or just show a complete working so I can see where I went wrong.
Thanks in advance for any help.
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