Cancellation Theorem

If $f(x)=g(x)$ when $x\ne c$, then ${\lim }_{x\to c}f(x)={\lim }_{x\to c}g(x)$ So, ${\lim }_{n\to \infty }$

As long as a and b are not 0, then $\frac{a}{b}$ is a real number

Applications

${\lim }_{h\to 0}\frac{0}{h}=0$ by cancellation theorem