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 Multiple Choice QuestionsShort Answer Type

191.

Show that:
integral subscript straight pi over 4 end subscript superscript straight pi over 4 end superscript open vertical bar sin space straight x close vertical bar dx space equals space 2 minus square root of 2



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 Multiple Choice QuestionsLong Answer Type

192.

Show that:
integral subscript negative 1 end subscript superscript 3 over 2 end superscript open vertical bar straight x space sinπ space straight x close vertical bar space dx space equals space 3 over straight pi plus 1 over straight pi squared



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 Multiple Choice QuestionsShort Answer Type

193.

Show that:
integral subscript 0 superscript 2 straight x square root of 2 minus straight x end root space equals fraction numerator 16 square root of 2 over denominator 15 end fraction

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194.

By using the properties of definite integrals, evaluate the following integral:
integral subscript 0 superscript 1 space straight x space left parenthesis 1 minus straight x right parenthesis to the power of straight n space dx

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195.

By using the properties of definite integrals, evaluate the following integral:
integral subscript 0 superscript straight pi over 2 end superscript fraction numerator sinx minus cosx over denominator 1 plus sinxcosx end fraction dx

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196.

Show that:
integral subscript 0 superscript straight pi over 2 end superscript 2 straight x space log space tanx space dx space equals space 0

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197.

By using the properties of definite integrals, evaluate the following integral:
integral subscript 0 superscript straight pi over 2 end superscript left parenthesis 2 space log space sinx space minus space log space sin space 2 straight x right parenthesis space dx

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198.

Show that:
integral subscript 0 superscript straight pi fraction numerator straight x space tanx over denominator secx space plus space cosx end fraction dx space equals space straight pi squared over 4

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199.

Show that:
integral subscript 0 superscript infinity log space open parentheses straight x plus 1 over straight x close parentheses. space fraction numerator dx over denominator 1 plus straight x squared end fraction space equals space straight pi space log space 2

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200.

Show that:
integral subscript 0 superscript 1 fraction numerator log space left parenthesis 1 plus straight x right parenthesis over denominator 1 plus straight x squared end fraction space equals space straight pi over 8 space log space 2


Let I = integral subscript 0 superscript 1 fraction numerator log left parenthesis 1 plus straight x right parenthesis over denominator 1 plus straight x squared end fraction dx
Put x = tan θ,    ∴ dx = sec2 θ dθ
When x = 0, tan θ = 0 ⇒ θ = 0
When x = 1,  tan space straight theta space equals space 1 space space space space space space space space rightwards double arrow space space space space straight theta space equals space straight pi over 4

therefore space space space straight I space equals space integral subscript 0 superscript straight pi over 4 end superscript space log left parenthesis 1 plus tanθ right parenthesis space dθ space                                         ...(1)
           equals space integral subscript 0 superscript straight pi over 4 end superscript log space open square brackets 1 plus tan open parentheses straight pi over 4 minus straight theta close parentheses close square brackets space dθ   open square brackets because space integral subscript 0 superscript straight a straight f left parenthesis straight x right parenthesis space dx space equals space integral subscript 0 superscript straight a straight f left parenthesis straight a minus straight x right parenthesis space dx close square brackets
           equals space integral subscript 0 superscript straight pi over 4 end superscript log open square brackets 1 plus fraction numerator 1 minus tanθ over denominator 1 plus tanθ end fraction close square brackets dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript log open square brackets fraction numerator 1 plus tanθ plus 1 minus tanθ over denominator 1 plus tanθ end fraction close square brackets dθ space equals space integral subscript 0 superscript straight pi over 4 end superscript log open parentheses fraction numerator 2 over denominator 1 plus tanθ end fraction close parentheses dθ

 equals space integral subscript 0 superscript straight pi over 4 end superscript log space 2 space dθ space space minus integral subscript 0 superscript straight pi over 4 end superscript log left parenthesis 1 plus tanθ right parenthesis space dθ
therefore space space space space straight I space equals space log space 2 integral subscript 0 superscript straight pi over 4 end superscript space 1. space dθ space minus space 1                                                          [because of (1)]
rightwards double arrow space 2 space straight I space space equals space log space 2 open square brackets straight theta close square brackets subscript 0 superscript straight pi over 4 end superscript space equals space open parentheses straight pi over 4 minus 0 close parentheses space log space 2 space rightwards double arrow space space 2 space straight I space equals space straight pi over 4 log 2 space space rightwards double arrow space space straight I equals straight pi over 8 log space 2

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