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Evaluate the following : limx→0[x|x|+x2] - Mathematics and Statistics

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Question

Evaluate the following :

`lim_(x -> 0)[x/(|x| + x^2)]`

Sum
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Solution

We know that |x| = x if x > 0

= – x if x < 0

∴ `lim_(x -> 0^+) [x/(|x| + x^2)]`

= `lim_(x -> 0) x/(x + x^2)`

= `lim_(x -> 0) x/(x(1 + x))`

= `lim_(x -> 0) 1/(1 + x)`   ...[∵ x → 0, ∴ x ≠ 0]

= `(lim_(x -> 0) 1)/(lim_(x -> 0) (1 + x))`

= `1/(1 + 0)`

= 1

`lim_(x -> 0^-) [x/(|x| + x^2)]`

= `lim_(x -> 0) x/(-x + x^2)`

= `lim_(x -> 0) x/(x(-1 + x))`

= `lim_(x -> 0) 1/(-1 + x)`   ...[∵ x → 0, ∴ x ≠ 0]

= `(lim_(x -> 0) 1)/(lim_(x -> 0) (-1 + x))`

= `1/(-1 + 0)`

= – 1

∴ `lim_(x -> 0^+) [x/(|x| + x^2)] ≠  lim_(x -> 0^-) [x/(|x| + x^2)] `

∴ `lim_(x -> 0) [x/(|x| + x^2)]` does not exist.

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Chapter 7: Limits - Miscellaneous Exercise 7.2 [Page 159]

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