I have this in my lecture:
How did $\lim_{x\rightarrow \infty} x^3 \left(\tan{\frac{1}{x}}\right)\left(\sin{\frac{3}{x^2}}\right)$ become $\lim_{x\rightarrow \infty}3\left(\frac{\tan{\frac{1}{x}}}{\frac{1}{x}}\right)\left(\frac{\sin{\frac{3}{x^2}}}{\frac{3}{x^2}}\right)$
Note the $x^3$ and the $3$ and denominator of the 2nd equation
UPDATE
The question is how come the $x^3$ became $3\left(\frac{1}{\frac{1}{x}}\right)\left(\frac{1}{\frac{3}{x^2}}\right)$