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Evaluate the following limits: limv→2[v2+v2-4v2-3v2+4] - Mathematics and Statistics

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Question

Evaluate the following limits: `lim_("v" -> sqrt(2))[("v"^2 + "v"sqrt(2) - 4)/("v"^2 - 3"v"sqrt(2) + 4)]`

Sum

Solution

`lim_("v" -> sqrt(2))[("v"^2 + "v"sqrt(2) - 4)/("v"^2 - 3"v"sqrt(2) + 4)]`

Consider, `"v"^2 + "v"sqrt(2) - 4 = "v"^2 + sqrt(2)"v" - 4`

= `"v"^2 + 2sqrt(2)"v" - sqrt(2)"v" - 4`

= `"v"("v" + 2sqrt(2)) - sqrt(2)("v" + 2sqrt(2))`

= `("v" + 2sqrt(2)) ("v" - sqrt(2))`

`"v"^2 - 3"v" sqrt(2) + 4 = "v"^2 - 3sqrt(2)"v" + 4`

= `"v"^2 - 2sqrt(2)"v" - sqrt(2)"v" + 4`

= `"v"("v" - 2sqrt(2)) - sqrt(2)("v" - 2sqrt(2))`

= `("v" - 2sqrt(2))("v" - sqrt(2))`

∴ `lim_("v" -> sqrt(2))[("v"^2 + "v"sqrt(2) - 4)/("v"^2 - 3"v"sqrt(2) + 4)]`

= `lim_("v" -> sqrt(2)) (("v" + 2sqrt(2))("v" - sqrt(2)))/(("v" - 2sqrt(2))("v" - sqrt(2))`

= `lim_("v" -> sqrt(2)) ("v" + 2sqrt(2))/("v" - 2sqrt(2))   ...[("As"  "v" -> sqrt(2)"," "v" ≠ sqrt(2)),(therefore "v" - sqrt(2) ≠ 0)]`

= `(sqrt(2) + 2sqrt(2))/(sqrt(2) - 2sqrt(2)`

= `(3sqrt(2))/(-sqrt(2)`

= – 3

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Chapter 7: Limits - EXERCISE 7.2 [Page 102]
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