What is the notation $f¢(x)$ stands for in context of derivatives? Consider the remark given here in the chapter 6 named APPLICATION OF DERIVATIVES from NCERT class 12 book

There is a more generalised theorem, which states that if $\mathbf{f¢(x) > 0}$
for $x$ in an interval excluding the end points and $f$ is continuous
in the interval, then $f$ is increasing. Similarly, if $\mathbf{f¢(x) < 0}$ for
$x$ in an interval excluding the end points and $f$ is continuous in
the interval, then $f$ is decreasing.

I am facing two issues in understanding it,

*

*What is the notation $f¢(x)$? Is it $f'(x)$?


*How is it a generalisation of the following theorem as told? (I can see no difference in both, if 1 is true)

Let $f$ be continuous on $[a, b]$ and differentiable on the open
interval $(a,b)$. Then
(a) $f$ is increasing in $[a,b]$ if $f ′(x) > 0$ for each $x \in (a,
 b)$
(b) $f$ is decreasing in $[a,b]$ if $f ′(x) < 0$ for each $x \in (a,
 b)$
(c) $f$ is a constant function in $[a,b]$ if $f ′(x) = 0$ for each $x
 \in (a, b)$


It is a misprinted character.
https://drive.google.com/file/d/0B8hXbvn1ab-BaXM0YjVhc285Z28/view?resourcekey=0-QLQBstamNZCN-LyLg9dXGQ
You can find the intention in this version/edition above.

