Evaluate  as the limit of a sum. from Mathematics Integrals

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 Multiple Choice QuestionsShort Answer Type

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1.

Evaluate integral from 1 to 2 of straight x space dx as the limit of a sum.


Comparing integral from 1 to 2 of straight x space dx space space with space integral from straight a to straight b of straight f left parenthesis straight x right parenthesis space dx comma space space we space get comma
               straight f left parenthesis straight x right parenthesis space equals space straight x comma space space space straight a space equals space 1 comma space space straight b space equals space 2
therefore space space space straight f left parenthesis straight a right parenthesis space equals space straight a comma space space straight f left parenthesis straight a plus straight h right parenthesis space equals space straight a plus straight h comma space space straight f left parenthesis straight a plus 2 straight h right parenthesis space equals space straight a plus 2 straight h comma space...... straight f left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis space equals space straight a plus left parenthesis straight n minus 1 right parenthesis straight h

Now   integral from straight a to straight b of straight f left parenthesis straight x right parenthesis space equals space stack Lt. straight h with straight h rightwards arrow 0 below left square bracket space straight f left parenthesis straight a right parenthesis plus straight f left parenthesis straight a plus straight h right parenthesis plus straight f left parenthesis straight a plus 2 straight h right parenthesis space plus space....... plus straight f left parenthesis straight a plus stack straight n minus 1 with bar on top space straight h right parenthesis right square bracket
                                                                                              where n h = b - a
rightwards double arrow        integral from straight a to straight b of xdx space equals space Lt with straight h rightwards arrow 0 below straight h left square bracket straight a plus straight a left parenthesis straight a plus straight h right parenthesis plus left parenthesis straight a plus 2 space straight h right parenthesis space plus space... plus left parenthesis straight a plus stack straight n minus 1 with bar on top straight h right parenthesis right square bracket

                          equals stack Lt space straight h with straight h rightwards arrow 0 below left square bracket left parenthesis straight a plus straight a plus straight a plus... to space straight n space terms right parenthesis space plus space straight h open curly brackets 1 plus 2 plus 3 plus.... plus left parenthesis straight n minus 1 right parenthesis close curly brackets right square bracket
                         equals space Lt with straight h rightwards arrow 0 below straight h open square brackets na plus straight h fraction numerator left parenthesis straight n minus 1 right parenthesis space left parenthesis straight n minus 1 plus 1 right parenthesis over denominator 2 end fraction close square brackets space space space space space open square brackets therefore 1 plus 2 plus 3 plus... plus straight n space equals space fraction numerator straight n left parenthesis straight n plus 1 right parenthesis over denominator 2 end fraction close square brackets
equals Lt with straight h rightwards arrow 0 below straight h open square brackets straight n space straight a plus fraction numerator straight n left parenthesis straight n minus 1 right parenthesis over denominator 2 end fraction straight h close square brackets space space equals Lt with straight h rightwards arrow 0 below open square brackets straight a space left parenthesis nh right parenthesis space plus space fraction numerator straight n space straight h left parenthesis nh minus straight h right parenthesis over denominator 2 end fraction close square brackets
equals Lt with straight h rightwards arrow 0 below open square brackets straight a space left parenthesis straight b minus straight a right parenthesis space plus space fraction numerator left parenthesis straight b minus straight a right parenthesis space left parenthesis straight b minus straight a minus straight h right parenthesis over denominator 2 end fraction close square brackets
equals space straight a left parenthesis straight b minus straight a right parenthesis space plus space fraction numerator left parenthesis straight b minus straight a right parenthesis space left parenthesis straight b minus straight a minus 0 right parenthesis over denominator 2 end fraction space equals space straight a space left parenthesis straight b minus straight a right parenthesis space plus fraction numerator left parenthesis straight b minus straight a right parenthesis squared over denominator 2 end fraction
equals space left parenthesis straight b minus straight a right parenthesis open square brackets straight a plus fraction numerator straight b minus straight a over denominator 2 end fraction close square brackets space equals space left parenthesis straight b minus straight a right parenthesis open parentheses fraction numerator straight b plus straight a over denominator 2 end fraction close parentheses
therefore space space space space space integral from straight a to straight b of xdx space equals space 1 half left parenthesis straight b squared minus straight a squared right parenthesis
Put a = 1,  b = 2
therefore space space space space space space space space space space space space space integral from 1 to 2 of xdx space equals space 1 half left parenthesis 4 minus 1 right parenthesis space equals space 3 over 2

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2. Evaluate the following definite integrals as limit of a sum.
integral from straight a to straight b of straight x space dx

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3. Evaluate the following definite integral as limit of a sum.
integral subscript 1 superscript 2 xdx



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4. Evaluate the following definite integral as limit of a sum.
integral subscript 0 superscript 5 left parenthesis straight x minus 1 right parenthesis dx


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5. Evaluate the following integral as the limit of a sum:
integral subscript 1 superscript 3 left parenthesis 2 straight x plus 3 right parenthesis dx
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6. Evaluate
integral subscript straight a superscript straight b straight x squared space dx  as the limit of sum.
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 Multiple Choice QuestionsLong Answer Type

7.

Evaluate  integral subscript 1 superscript 3 straight x squared space dx as the limit of a sum.

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8.

Evaluate integral subscript 1 superscript 4 left parenthesis straight x squared minus straight x right parenthesis space dx  as the limit of a sum.

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9.

Evaluate integral subscript 1 superscript 2 space left parenthesis 3 straight x squared plus 5 straight x right parenthesis space dx as limit of sums.

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10.

Evaluate integral subscript 1 superscript 3 space left parenthesis 3 straight x squared plus 2 straight x right parenthesis space dx as the limit of sums.

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