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Discuss the continuity of the function f, where f is defined by ,,,f(x)={-2,ifx≤-12x,if-1<x≤12,ifx>1 - Mathematics

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प्रश्न

Discuss the continuity of the function f, where f is defined by `f(x) = {(-2,"," if x <= -1),(2x, "," if -1 < x <= 1),(2, "," if x > 1):}`

बेरीज

उत्तर

`f(x) = {(-2,"," if x <= -1),(2x, "," if -1 < x <= 1),(2, "," if x > 1):}`

f(x) = -2 for x < 1;

-1 < x < 1, f(x) = 2x and

x > 1, f(x) = 2 is a polynomial function.

So this is a function.

At x = - 1,

`lim_(x -> 1^-) f(x) = lim_(x -> 1^-)` (-2) = -2

`lim_(x -> 1^+) f(x) = lim_(x -> 1^+)` (2x)

= `lim_(h -> 0)` [2 (-1 + h)]

= `lim_(h -> 0)` (-2 + 2h)

= - 2 + 0

= - 2

f(-1) = -2

Hence, f is continuous at x = -1.

At x = 1,

`lim_(x -> 1^-) f(x) = lim_(x -> 1^-)` (2x)

= `lim_(h -> 0)` [2(1 - h)]

= `lim_(h -> 0)` (2 - 2h) = 2 - 2 x 0 = 2

`lim_(x -> 1^+) f(x) = lim_(x -> 1^+)` (2) = 2

f(1) = 2 x 1 = 2

Hence, f is continuous at x = 1.

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पाठ 5: Continuity and Differentiability - Exercise 5.1 [पृष्ठ १६०]

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एनसीईआरटी Mathematics [English] Class 12
पाठ 5 Continuity and Differentiability
Exercise 5.1 | Q 16 | पृष्ठ १६०

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