MCQ
The differential coefficient of the function $|x - 1| + |x - 3|$ at the point $x = 2$ is
  • A
    $-2$
  • $0$
  • C
    $2$
  • D
    Undefined

Answer

Correct option: B.
$0$
b
(b) $f(x) = |x - 1| + |x - 3|$

$f(x) = \left\{ {\begin{array}{*{20}{c}}{ - (x - 1) - (x - 3),}&{x < 1}\\{(x - 1) - (x - 3),}&{x > 1}\\{(x - 1) - (x - 3),}&{x < 3}\\{(x - 1) + (x - 3),}&{x > 3}\end{array}} \right.$

$ = \left\{ {\begin{array}{*{20}{c}}{4 - 2x,}&{x < 1}\\{2\,\,\,\,\,\,\,\,\,,}&{1 < x < 3}\\{2x - 4,}&{x > 3}\end{array}} \right.$

At $x = 2$, $f(x) = $ $2$ .

Hence $\,f'(x) = 0$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free