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∫1x2-8x-20 dx

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Question

`int 1/sqrt(x^2 - 8x - 20)  "d"x`

Sum
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Solution

Let I = `int 1/sqrt(x^2 - 8x - 20)  "d"x`

= `int 1/sqrt(x^2 - 2.4x + 16 - 16 - 20)  "d"x`

= `int ("d"x)/sqrt((x - 4)^2 - 36)  "d"x`

= `int ("d"x)/sqrt((x - 4)^2 - 6^2)  "d"x`

= `log|(x - 4) + sqrt((x - 4)^2 - 6^2)| + "c"`

∴ I = `log|(x - 4) + sqrt(x^2 - 8x - 20)| + "c"`

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Chapter 1.5: Integration - Q.5

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