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Evaluate the following. ∫14x2-1 dx - Mathematics and Statistics

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Question

Evaluate the following.

`int 1/(4"x"^2 - 1)` dx

Sum

Solution

Let I = `int "dx"/(4"x"^2 - 1)`

`= 1/4 int "dx"/("x"^2 - 1/4)`

`= 1/4 int "dx"/("x"^2 - (1/2)^2)`

`= 1/4 xx 1/(2 xx 1/2) log |("x" - 1/2)/("x" + 1/2)|` + c

∴ I = `1/4` log `|("2x" - 1)/("2x" + 1)|` + c

Alternate Method:

Let I = `int "dx"/(4"x"^2 - 1) = int "dx"/((2"x"^2) - (1)^2)`

`= 1/(2 xx 1) xx 1/2 log |("2x" - 1)/("2x" + 1)|` + c

∴ I = `1/4` log `|("2x" - 1)/("2x" + 1)|` + c

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Chapter 5: Integration - EXERCISE 5.4 [Page 129]
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