# Problem of the Week

## Updated at Nov 7, 2016 11:48 AM

This week we have another calculus problem:

How can we find the derivative of $$\sin{x}+9x$$?

Let's start!

$\frac{d}{dx} \sin{x}+9x$

 1 Use Sum Rule: $$\frac{d}{dx} f(x)+g(x)=(\frac{d}{dx} f(x))+(\frac{d}{dx} g(x))$$.$(\frac{d}{dx} \sin{x})+(\frac{d}{dx} 9x)$2 Use Trigonometric Differentiation: the derivative of $$\sin{x}$$ is $$\cos{x}$$.$\cos{x}+(\frac{d}{dx} 9x)$3 Use Power Rule: $$\frac{d}{dx} {x}^{n}=n{x}^{n-1}$$.$\cos{x}+9$Donecos(x)+9