120. Find $\lim _{x \rightarrow 3}\left(x^{2}-7 x+4\right)$.
Solution. To find the limit of the given function, we will replace the argument $x$ with its limiting value:

$$
\lim _{x \rightarrow 3}\left(x^{2}-7 x+4\right)=3^{2}-7 \cdot 3+4=-8
$$