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Examine the continuity of the function f(x) = x3 + 2x2 – 1 at x = 1 - Mathematics

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प्रश्न

Examine the continuity of the function f(x) = x3 + 2x2 – 1 at x = 1

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उत्तर

We have, f(x) = x3 + 2x2 – 1 

For continuity at x = 1

∴ R.H.L. = `lim_(x -> 1^+) "f"(x)`

= `lim_("h" -> 0) "f"(1 + "h")`

= `lim_("h" -> 0) [(1 + "h")^3 + 2(1 + "h")^2 - 1]` = 2

And L.H.L. = `lim_(x -> 1^-) "f"(x)`

= `lim_("h" -> 0) "f"(1 - "h")`

= `lim_("h" -> 0)[(1 - "h")^3 + 2(1 - "h")^2 - 1]` = 2

Also f(1) = 1 + 2 – 1 = 2

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

Thus f(x) is continuous at x = 1

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अध्याय 5: Continuity And Differentiability - Exercise [पृष्ठ १०७]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 12
अध्याय 5 Continuity And Differentiability
Exercise | Q 1 | पृष्ठ १०७

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