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F(x) = kk,if,if{1+kx-1-kxx, if-1≤x<02x+1x-1, if 0≤x≤1 at x = 0 - Mathematics

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प्रश्न

f(x) = `{{:((sqrt(1 + "k"x) - sqrt(1 - "k"x))/x",",  "if" -1 ≤ x < 0),((2x + 1)/(x - 1)",",  "if"  0 ≤ x ≤ 1):}` at x = 0

योग
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उत्तर

We have f(x) = `{{:((sqrt(1 + "k"x) - sqrt(1 - "k"x))/x",",  "if" -1 ≤ x < 0),((2x + 1)/(x - 1)",",  "if"  0 ≤ x ≤ 1):}`

L.H.L. = `lim_(x -> 0^-) (sqrt(1 + "k"x) - sqrt(1 - "k"x))/x`

= `lim_(x -> 0^-) ((sqrt(1 + "k"x) - sqrt(1 - "k"x))/x) * ((sqrt(1 + "k"x) + sqrt(1 - "k"x))/(sqrt(1 + "k"x) + sqrt(1 - "k"x)))`

= `lim_(x -> 0^-) (1 + "k"x - 1 + "k"x)/(x[sqrt(1 + "k"x) + sqrt(1 + "k"x)])`

= `lim_("h" -> 0) (2"k")/(x[sqrt(1 + "k"(0 - "h")) + sqrt(1 - "k"(0 - "h")]`

= `lim_("h" -> 0) (2"k")/(sqrt(1 - "kh") + sqrt(1 + "kh")`

= `(2"k")/2`

= k

R.H.L. = `lim_(x -> 0^+) (2x + 1)/(x - 1)`

= `lim_("h" -> 0) (2(0 + "h") + 1)/((0 + "h") - 1)`

= `lim_("h" -> 0) (2"h" + 1)/("h" - 1)`

= – 1

Also f(0) = `(2 xx 0 + 1)/(0 - 1)` = – 1

We must have L.H.L. = R.H.L. = f(0)

⇒ k = – 1

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अध्याय 5: Continuity And Differentiability - Exercise [पृष्ठ १०८]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 12
अध्याय 5 Continuity And Differentiability
Exercise | Q 13 | पृष्ठ १०८

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