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September 19, 2014

September 19, 2014

Posted by **Adam** on Monday, April 26, 2010 at 11:14pm.

What is the derivative? Im doing online homework and i keep getting an incorrect answer. How do you work out this problem correctly? thanks

- calc -
**Reiny**, Monday, April 26, 2010 at 11:15pmyou must know that if

y = a cos kx, where k is a constant, then

dy/dx = -a(k)sin kx

so f(x) = 8cos 4x

f'(x) = -32sin 4x

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