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Discuss the continuity of the following function at the point indicated against them : f(x) =e1x-1e1x+1, for x≠0=1,for x=0} at x = 0

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Question

Discuss the continuity of the following function at the point indicated against them :

f(x)  `{:(=("e"^(1/x) - 1)/("e"^(1/x) + 1)",",  "for"  x ≠ 0),(= 1",", "for"  x = 0):}}` at x = 0

Sum
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Solution

f(0) = 1   ...(Given)

`lim_(x -> 0^-) "f"(x) =  lim_("h" -> 0) ("e"^(1/((0 - "h"))) - 1)/("e"^(1/((0 - "h"))) + 1)`

= `lim_("h" -> 0) ("e"^((-1)/"h" - 1))/("e"^((-1)/"h" + 1))`

= `lim_("h" -> 0) ("e"^(1/(1/"h")) - 1)/("e"^(1/(1/"h")) + 1)`

= `(0 - 1)/(0 + 1)` 

= – 1

`lim_(x -> 0^+) "f"(x) =  lim_("h" -> 0) ("e"^(1/((0 + "h"))) - 1)/("e"^(1/((0 + "h"))) + 1)`

= `lim_("h" -> 0) ("e"^(1/"h") - 1)/("e"^(1/"h") + 1)`

=  `lim_("h" -> 0)  ("e"^(1/"h")(1 - 1/("e"^(1/"h"))))/("e"^(1/"h")(1 + 1/("e"^(1/"h")))`

= `(1 - 0)/(1 + 0)`

= 1

`lim_(x -> 0^-) "f"(x) ≠ lim_(x -> 0^+) "f"(x)`

∴ f(x) is discontinuous at x = 0

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Chapter 8: Continuity - EXERCISE 8.1 [Page 173]

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