Clearly u = cos x and v = sin x are solutions of y'' + y = 0. Show that and z = uv are solutions of z''' + 4z' = 0

I dont understand how to start this off. Im not asking for the answer just trying to understand what is going on or what to do.

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- Apr 6th 2010, 10:18 PMonemoreu and v are solutions
Clearly u = cos x and v = sin x are solutions of y'' + y = 0. Show that and z = uv are solutions of z''' + 4z' = 0

I dont understand how to start this off. Im not asking for the answer just trying to understand what is going on or what to do. - Apr 7th 2010, 02:09 AMtom@ballooncalculus
Is what's meant to be clear, clear? Just in case a picture helps...

http://www.ballooncalculus.org/asy/diffChain/f2.png

... differentiating downwards.

__Spoiler__:

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Don't integrate - balloontegrate!

Balloon Calculus; standard integrals, derivatives and methods

Balloon Calculus Drawing with LaTeX and Asymptote! - Apr 7th 2010, 03:57 AMHallsofIvy