f(x) = sinx/x^3 i obtained f'(x) = (x²cos-3xsinx)/x^4 is that correct :O?
Follow Math Help Forum on Facebook and Google+
Using the quotient rule, $\displaystyle \frac{d}{dx} \frac{\sin x}{x^3} =$ $\displaystyle \frac{x^3 \cos x - 3x^2 \sin x}{x^6} =$ $\displaystyle \frac{x \cos x - 3 \sin x}{x^4}$ which is not quite what you had, but I think you had the right idea.
View Tag Cloud