Continuity and Differentiability — Class 12 Maths Solution

exemplar objective MCQ NCERT Exemp. Ex.5.3 ,Q.87,Page 114
Question

The function $f(x) = {e^{|x|}}$ is

  • (a) continuous everywhere but not differentiable at $x = 0$ ✓ Correct
  • (b) continuous and differentiable everywhere
  • (c) not continuous at $x = 0$
  • (d) None of the above
Step-by-step Solution
Correct answer: option (a)

Let $u(x) = |x|$ and $v(x) = {e^x}$

therefore,$f(x) = {\mathop{\rm vou}\nolimits} (x) = v[u(x)]$
$= v|x| = {e^{|x|}}$

Since, $u(x)$ and $v(x)$ are both continuous functions.

So, $f(x)$ is also continuous function but $u(x) = |x|$ is not differentiable at $x = 0,$ whereas $v(x) = {e^x}$ is differentiable at everywhere.

Hence, $f(x)$ is continuous everywhere but not differentiable at $x = 0$.

NCERT & Exemplar solution for CBSE Class 12 Mathematics, Continuity and Differentiability. Curated by Sachin Sharma. Free for all students.