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Evaluate: ∫log(x2+x) dx - Mathematics and Statistics

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Question

Evaluate: `int log ("x"^2 + "x")` dx

Sum

Solution

Let I = `int log ("x"^2 + "x")` dx

`= int log ("x"^2 + "x") * 1 * "dx"`

`= log ("x"^2 + "x") int 1 * "dx" - int {"d"/"dx" log ("x"^2 + "x") int 1 * "dx"}`dx

`= log ("x"^2 + "x") * "x" - int 1/("x"^2 + "x") * (2"x" + 1) * "x" * "dx"`

`= "x" * log ("x"^2 + "x") - int 1/("x"("x + 1")) * (2"x" + 1) * "x" * "dx"`

`= "x" * log ("x"^2 + "x") - int("2x + 1")/("x + 1")`dx

`= "x" * log ("x"^2 + "x") - int((2"x" + 2) - 1)/("x + 1")` dx

`= "x" * log ("x"^2 + "x") - int[(2("x + 1"))/("x + 1") - 1/("x + 1")]` dx

`= "x" * log ("x"^2 + "x") - int[2 - 1/"x + 1"]` dx

`= "x" * [log("x"^2 + "x")] - (2"x" - log |"x + 1"|) + "c"`

∴ I = `"x" * [log("x"^2 + "x")] - 2"x" + log |"x + 1"|` + c

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Chapter 5: Integration - MISCELLANEOUS EXERCISE - 5 [Page 139]

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Balbharati Mathematics and Statistics 1 (Commerce) [English] 12 Standard HSC Maharashtra State Board
Chapter 5 Integration
MISCELLANEOUS EXERCISE - 5 | Q IV. 4) iv) | Page 139
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