calculus and trigonometry

Dec 2008
161
12
Australia
If f(x) = (ax + b) sinx + (cx +d ) cosx
find constants a, b, c, d, such that f'(x) = xcosx

How do I do this?

thanks
 
Mar 2010
165
40
Planet earth.
If f(x) = (ax + b) sinx + (cx +d ) cosx
find constants a, b, c, d, such that f'(x) = xcosx

How do I do this?

thanks
Find the derivative and set it equal to \(\displaystyle x \, cos(x)\). Then, solve the last equation for a,b,c and d.
 
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