Q. 35.0( 2 Votes )

Find which of the functions is continuous or discontinuous at the indicated points:

Answer :



We need to check its continuity at x = 0

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 (h0)

Now according to above theory-

f(x) is continuous at x = 0 if -


LHL = {using equation 1}

As we know cos(-θ) = cos θ


1 – cos 2x = 2sin2x


As this limit can be evaluated directly by putting value of h because it is taking indeterminate form (0/0)

As we know,

LHL = 2 × 12 = 2 …(2)

Similarly, we proceed for RHL-




Again, using sandwich theorem, we get -

RHL = 2 × 12 = 2 …(3)


f (0) = 5 …(4)

Clearly from equation 2, 3 and 4 we can say that

f(x) is discontinuous at x = 0

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