Find which of the functions is continuous or discontinuous at the indicated points:
f(x) = |x| + |x – 1| at x = 1
Given,
f(x) = |x| + |x – 1| …(1)
We need to check its continuity at x = 1
A function f(x) is said to be continuous at x = c if,
Left hand limit(LHL at x = c) = Right hand limit(RHL at x = c) = f(c).
Mathematically we can represent it as-
Where h is a very small number very close to 0 (h→0)
Now according to above theory-
f(x) is continuous at x = 1 if -
Clearly,
LHL = {using eqn 1}
⇒ LHL =
∵ h > 0 as defined above and h→0
∴ |-h| = h
And (1 – h) > 0
∴ |1 – h| = 1 - h
⇒ LHL =
∴ LHL = 1 …(2)
Similarly we proceed for RHL-
RHL = {using eqn 1}
⇒ RHL =
∵ h > 0 as defined above and h→0
∴ |h| = h
And (1 + h) > 0
∴ |1 + h| = 1 + h
⇒ RHL =
∴ RHL = 1 + 2(0) = 1 …(3)
And,
f(1) = |1|+|1-1| = 1 {using eqn 1} …(4)
Clearly from equation 2 , 3 and 4 we can say that
∴ f(x) is continuous at x = 1