Write an example of a function which is everywhere continuous but fails to differentiable exactly at five points.
Question:
Write an example of a function which is everywhere continuous but fails to differentiable exactly at five points.
Solution:
$f(x)=|x|+|x+1|+|x+2|+|x+3|+|x+4|$
The above function is continuous everywhere but not differentiable at x = 0, 1, 2, 3 and 4