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If ,,f(x)={x+2, x≤-1cx2,x>-1, find 'c' if limx→-1f(x) exists

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Question

If `f(x) = {{:(x + 2",",  x ≤ - 1),(cx^2",", x > -1):}`, find 'c' if `lim_(x -> -1) f(x)` exists

Sum
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Solution

Given, `f(x) = {{:(x + 2",",  x ≤ - 1),(cx^2",", x > -1):}`

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

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

= `lim(h -> 0) (-1 - h + 2)`

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

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

= `lim_(h -> 0) c(-1 + h)^2` = c

Since the limits exist.

∴ L.H.L = R.H.L

∴ c = 1

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Chapter 13: Limits and Derivatives - Exercise [Page 242]

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NCERT Exemplar Mathematics [English] Class 11
Chapter 13 Limits and Derivatives
Exercise | Q 53 | Page 242

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