Question

fX = 3+|x| find its critical point when x belongs to real

Answer 1

To find minimum, we simply observe that for x >= 0, f(x) = 3 + x >= 3 and for x<=0, f(x) = 3 - x >= 3. Also, at x = 0, f(x) = 3.  Hence, f(x) >= 3 and f(0) = 3 and so the minimum value of f(x) is 3.