### Calculus

Topics within Calculus

## Before you go

Before you go off to derivatives (oh, how much fun) there's a few more things you should know.

If you skip this, and I know it's tempting, you'll be confused later. I'll reference this page later, so you better read it now instead of coming back to it when you've already started derivatives.

That said, these are really just some really nice and simple answers to common problems, just like when you learned in trigonometry that $\sin{30}=\frac{1}{2}$. (You did, right?)

### Infinite Series

##### Referenced later as IS#
1. $$\ln{(x+1)}=x-\frac{x^2}{2}+\frac{x^3}{3}-\frac{x^4}{4}+\cdots\pm\frac{x^{\infty}}{\infty}$$

2. $$e^x=1+\frac{x}{1!}+\frac{x^2}{2!}+\frac{x^3}{3!}+\frac{x^4}{4!}+\cdots+\frac{x^{\infty}}{\infty!}$$

### Limits Identities

##### Referenced later as LI#
1. $$\lim_{x\to 0}\frac{a^{x}-1}{x}=\ln{a}$$

2. $$\lim_{x\to 0}\frac{e^x-1}{x}=1$$

3. $$\lim_{x\to 0}\frac{\sin{x}}{x}=1$$

4. $$\lim_{x\to 0}\frac{\cos{x}-1}{x}=0$$

5. $$\lim_{x\to 0}(1+x)^{\frac{1}{x}}=e$$

Can you use LI1 to prove LI2? How about LI3 to prove LI4?

(Hint: Yes you can, now do it!)