If $f(2)=4$ and $f^{\prime}(2)=1$, then $$ \lim _{x \rightarrow 2} \frac{x f(2)-2 f(x)}{x-2} $$ is equal to
If $f(2)=4$ and $f^{\prime}(2)=1$, then
$$
\lim _{x \rightarrow 2} \frac{x f(2)-2 f(x)}{x-2}
$$
is equal to
- $-2$
- $1$
- $2$
- $3$
Solution
Given that, $f(2)=4$ and $f^{\prime}(2)=1$
$
\begin{aligned}
\therefore \quad & \lim _{x \rightarrow 2} \frac{x f(2)-2 f(x)}{x-2} \\
& =\lim _{x \rightarrow 2} \frac{x f(2)-2 f(2)+2 f(2)-2 f(x)}{x-2} \\
= & \lim _{x \rightarrow 2} f(2)-2 \lim _{x \rightarrow 2} \frac{f(x)-f(2)}{x-2} \\
= & f(2)-2 f^{\prime}(2) \\
= & 4-2(1) \\
= & 2
\end{aligned}
$
Asked in: AP EAMCET 2008
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