$f(x) = \frac{\sin x\ \cos x}{2x}$

A cura di: Administrator

$f(x) = frac{sin x cos x}{2x}$ $f'(x) =$ $frac{[cos x cos x + sin x (-sin x)] 2x – (sin x cos x) 2}{(2x)^2} =$ $frac{(cos^2 x – sin^2 x) 2x – (2sin x cos x)}{4x^2} =$ $frac{2x cos 2x – sin 2x}{4x^2}$