Find derivative. y = [cos(pix) + 1]/x My Answer is y' = - [pixsin(pix) minus cos(pix) + 1]/x^2 Book's answer is y' = - [pixsin(pix) plus cos(pix) + 1]/x^2 Where did the plus come from?
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It's because it should be $\displaystyle \displaystyle \frac{ - \pi x \sin{( \pi x )} - \left[ \cos{( \pi x ) } + 1 \right] }{x^2}$.
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