## Calculus (3rd Edition)

We have $$|3 x-12|=3|x-4|$$ Since $|3x-12|$ is a multiple of $|x-4|$, then we see that $|3x-12|$ is small by taking $x$ sufficiently close to $4$. Hence, we have $$\lim _{x \rightarrow 4} 3x=12.$$