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For what value of λ is the function defined by ,,f(x)={λ(x2-2x) ,ifx≤04x+1,ifx>0 continuous at x = 0? What about continuity at x = 1? - Mathematics

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प्रश्न

For what value of `lambda` is the function defined by `f(x) = {(lambda(x^2 - 2x),  "," if x <= 0),(4x+ 1, "," if x > 0):}`  continuous at x = 0? What about continuity at x = 1?

योग

उत्तर

`f(x) = {(lambda(x^2 - 2x),  "," if x <= 0),(4x+ 1, "," if x > 0):}`

If f(x) is continuous at x = 0, it implies:

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

`=> (0^2 - 2(0)) = (4 (0) + 1) = (0^2 - 2 (0))`

`=> 0 = 1 =  0`

Which cannot be true, i.e. for any value of `lambda` this function is not continuous at x = 0.

If f(x) is continuous at x = 1, this implies:

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

⇒ 4(1) + 1 = 4(1) + 1 = 4(1) + 1

⇒ 5 = 5 = 5

Which is always true, i.e. for any value of `lambda` this function is continuous at x = 1.

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

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एनसीईआरटी Mathematics [English] Class 12
अध्याय 5 Continuity and Differentiability
Exercise 5.1 | Q 18 | पृष्ठ १६०

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