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Evaluate the following limits: limx→0[1+x2-1+x1+x3-1+x] - Mathematics and Statistics

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Question

Evaluate the following limits:  `lim_(x -> 0)[(sqrt(1 + x^2) - sqrt(1 + x))/(sqrt(1 + x^3) - sqrt(1 + x))]`

Sum
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Solution

`lim_(x -> 0)[(sqrt(1 + x^2) - sqrt(1 + x))/(sqrt(1 + x^3) - sqrt(1 + x))]`

= `lim_(x -> 0) ((sqrt(1 + x^2) - sqrt(1 + x))(sqrt(1 + x^3) + sqrt(1 + x))(sqrt(1 + x^2) + sqrt(1 + x)))/((sqrt(1 + x^3) - sqrt(1 + x))(sqrt(1 + x^3) + sqrt(1 + x))(sqrt(1 + x^2) + sqrt(1 + x))`

= `lim_(x -> 0) ([1 + x^2 - (1 + x)](sqrt(1 + x^3) + sqrt(1 + x)))/([1 + x^3 - (1 + x)](sqrt(1 + x^2) + sqrt(1 + x))`

= `lim_(x -> 0) (x(x - 1)(sqrt(1 + x^3) + sqrt(1 + x)))/(x(x^2 - 1)(sqrt(1 + x^2) + sqrt(1 + x))`

= `lim_(x -> 0) (x(x - 1)(sqrt(1 + x^3) + sqrt(1 + x)))/(x(x - 1)(x + 1)(sqrt(1 + x^2) + sqrt(1 + x)))`

= `lim_(x -> 0) (sqrt(1 + x^3) + sqrt(1 + x))/((x + 1)(sqrt(1 + x^2) + sqrt(1 + x))`      ...[∵ x → 0, ∴ x ≠ 0, ∴ x – 1 ≠ 0]

= `(sqrt(1 + 0^3) + sqrt(1 + 0))/((0 + 1)(sqrt(1 + 0^2) + sqrt(1 + 0))`

= `(1 + 1)/(1(1 + 1)`

= 1

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Chapter 7: Limits - EXERCISE 7.3 [Page 103]
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