Integrais_-_Exercícios_Resolvidos

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    Exerccios

    1.) Resolva as Integrais

    a) ( 10x + x 4/5 + x ) dx= 10xdx + x 4/5 dx+ x dx= 10 x1/2dx + x 4/5 dx+ x dx

    = 10. x3/2 + x9/5 + x1/23/2 9/5 1/2

    = 10. 2 x3/2

    + 5 x9/5

    + 2x1/2

    3 9

    = 20x3/2 + 5 x9/5 + 2x + c

    3 9

    b) ( 3x + x 1/5 + x3 ) dx4

    = x1/3dx + x 1/5dx + x3dx4

    = 1 x1/3dx + x 1/5dx + x3dx4

    = 1 . x4/3 + x6/5 + x-24 4/3 6/5 -2

    = 1 . 3 . x4/3 + 5 x6/5 - 1 . 1

    4 4 6 2 x2

    = 3 x4/3 + 5 x6/5 1 + c16 2x2

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    c) (x0,2 + x0,5 + x4 x-3) dx

    = x0,2 dx + x0,5 dx + x4 dx x-3 dx

    = x1/2 + x1/5 + x5 x-2 1/5 5 -2

    = 2. x0,5 + 5 . x0,2 + 1 . x5 + 11 1 5 x2

    2

    = 2x0,5 + 5x0,2 + 0,2x5 + 0,5x2 + c

    d)

    10

    1 (4 + x2 + 3x) dx

    10 10 10

    1 4 dx +1 x2 dx + 1 3x dx

    10= 4x + x3 + 3x2 = (4 . 10 + 103 + 3.102) - (4 . 1 + 13 + 3.12)3 2 1 3 2 3 2

    = 40 + 1000 + 300 4 1 33 2 3 2

    = 240 + 2.000 + 900 24 2 96

    = 3.1056

    = 517,5

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    e)

    8

    1 1 dxx3

    8

    1 x-3 dx

    8= x -2 = 1 = 1 . 1 = - 1 = ( - 1 ) - ( - 1 )

    -2 x2 x2 -2 2x2 1 2.82 2.12-2 = - 1 + 1 = - 1 + 64 = 63 = 0,49

    128 2 128 128

    f)

    0

    -1 (x2 + x3 + 2) dx0 0 0

    -1 x2dx + -1 x3dx + -1 2dx

    0

    x3

    + x4

    + 2x = (03

    + 04

    + 2.0) (-13

    + -14

    + 2.-1)3 4 -1 3 4 3 4

    = 1 1 + 2 = 4 3 + 24 = 25 = 2,083 4 12 12

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    g)

    1

    0 (1 x + 1 x2 + 5x + 1) dx2 4

    1 1 1 1

    = 10 xdx + 1 0 x2dx + 5 0 xdx + 1 0 dx2 4

    = 1 . 1 x2 + 1 . 1 x3 + 5 . 1 x2 + x2 2 4 3 2

    1

    = 1 x2 + 1 x3 + 5 x2 + x = ( 1 . 12 + 1 . 13 + 5 . 12 + 1 ) - 04 12 2 0 4 12 2

    = 1 + 1 + 5 + 1 = 3 + 1 + 30 + 12 = 46 = 3,834 12 2 12 12

    h)

    3

    1 (5x 2x2 + 3) dx

    3 3 3

    1 5x - 1 2x2 dx + 1 3 dx3

    = 5 x2 2x3 + 3x = ( 5 . 32 2 . 33 + 3 . 3 ) (5 . 12 2 . 13 + 3 . 1)2 3 1 2 3 2 3

    = 45 54 + 9 5 + 2 32 3 2 3

    = 135 108 + 54 15 + 4 186

    = 52 = 8,676

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    i)

    3a

    a ( a + x) dx3a 3a

    a a dx + a x dx3a 3a

    a a dx + a x dx3a

    a.x + x2 = a.3a + 3a2 (a . a + a2)2 a 2 2

    = 3a2 + 3a2 a2 a2 = 6a2 + 3a2 2a2 a2 = 6a2 = 3a22 2 2 2

    j)

    4

    1 (x x) dx4 4

    1 x1/2 - 1 x dx4

    x3/2

    x2

    = 2 x3/2

    x2

    = ( 2 (4)3/2

    42

    ) ( 2 (1)3/2

    12

    )3 2 3 2 1 3 2 3 22 = ( 2 (22)3/2 16 ) 2 + 1 =

    3 2 3 2= 2 . 23 8 - 2 + 1

    3 3 2= 16 8 2 + 1 = 32 48 4 + 3 = - 17 = - 2,83

    3 3 2 6 6

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    k)

    1

    -3 ( 1 - 1 ) dxx3 x2

    1

    -3 ( 1 - 1 ) dx = x-3 x-21 1

    x-3 x-2

    1

    -3 (x-3 x-2) dx

    1 1

    -3 x-3 dx - -3 x

    -2 dx

    1

    = x-2 x-1 = 1 - 1 = ( 1 - 1 ) ( 1 - 1 ) = 11 - ( 1 + 1 ) = - 1 - 1 = -1 3 = - 4x2 x -3 12 1 -32 -3 9 3 9 3 9 9

    l)

    1

    -1 ( 3x2 2x3) dx1 1

    -1 3x2 dx - -1 2x3 dx1

    = 3x3 2x4 = x3 1x4 = ( 13 1.14 ) ( -13 1. -14) = 1 1 ( - 1 1 )3 4 2 -1 2 2 2 2

    = 1 1 + 1 + 1 = 2 1 + 2 + 1 = 4 = 22 2 2 2

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    m)

    3

    2 ( 2x3 1x + 4) dx3

    3 3 3

    2 2x3dx - 2 1x dx + 2 4 dx3

    3

    = 2x4 1 . x2 + 4x = 1x4 x2 + 4x = ( 1 . 34 32 + 4.3) (1 . 24 22 + 4.2)4 3 2 2 6 2 2 6 2 6

    = 81 9 + 12 ( 8 4 + 8)2 6 6

    = 81 9 + 12 8 + 4 82 6 6

    = 243 9 + 72 48 + 4 486

    = 214 = 35,676

    n)

    1

    1 ( x3 - x2 + 1) dx1 1 1

    1 x3 dx - 1 x2 dx + 1 dx1

    = x4 - x3 + x = ( 14 13 + 1) (14 13 + 1) = 04 3 1 4 3 4 3

    n

    Conclui-se que n f(x) dx = 0

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    o)

    2 1

    1 x2 dx e 2 (x2 dx2 2

    1 x2 dx = x3 = 23 13 = 8 - 1 = 73 1 3 3 3 3 3

    1 1

    2 x2 dx = x3 = 13 23 = 1 - 8 = - 73 2 3 3 3 3 3

    m n

    Conclui-se que

    n f(x) dx = -

    m f(x) dx

    2.) Dada a funo de custo marginal e custo fixo, determine as funes deCT e CM.

    a)Cmg = 5 + 2x, CF = 2b)Cmg = x3 6x2 + 7x, CF = 3c)Cmg = 900 360x + 9x2, CF = 30a)

    CT = CmgCT = (5 + 2x) dxCT =5 dx + 2 x1/2 dx

    CT = 5x + 2.x3/23/2

    CT = 5x + 2 . 2 x3/23

    CT = 5x + 4 x3/2 + c3

    CT = CF p/ x = 0

    2 = 5. 0 + 4 03/2 + c3

    2 = c

    CT = 5x + 4 x3/2 + 23

    CM = CTx

    CM = 5x + 4 x3/2 + 23x

    CM = 5 + 4 x1/2 + 23 x

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    b)

    CT = CmgCT = (x3 6x2 + 7x) dxCT = x3 dx - 6x2 dx + 7x dx

    CT = x4 6x3 + 7x2 + c4 3 2

    CT =1x4 2x3 + 7x2 + c4 2

    CT = CF p/ x = 0

    3 = c

    CT =1x4 2x3 + 7x2 + 34 2

    CT = 0,25x4 2x3 + 3,5x2 + 3

    CM = CTx

    CM = 0,25x4 2x3 + 3,5x2 + 3

    x

    CM = 0,25x3 2x2 + 3,5x + 3x

    c)

    CT =

    Cmg

    CT = (900 360x + 9x2) dxCT = 900 dx - 360x dx + 9x2 dx

    CT = 900x 360x2 + 9x32 3

    CT = 900x 180x2 + 3x3 + c

    CT = CF p/ x = 0

    30 = c

    CT = 900x 180x2 + 3x3 + 30

    CM = CTx

    CM = 900x 180x2 + 3x3 + 30x

    CM = 900 180x + 3x2 + 30x

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    3.) Um monopolista tem a seguinte curva de rendimento marginalRmg = 1.000 10x. Determine RT e RM p/ x = 10, sabendo-se que a RT = 95para x = 1.

    RT =

    Rmg

    RT = (1.000 10x) dx

    RT = 1.000 dx 10x dx

    RT = 1.000x 10x22

    RT = 1.000x 5x2 + c

    95 = 1.000 . 1 5 . 12 + c

    95 = 1.000 5 + c

    95 1.000 + 5 = c

    - 900 = c

    RT = 1.000x 5x2 900

    RT x=10 = 1.000 . 10 5 . 102 - 900

    RT x=10 = 10.000 500 900

    RT x=10 = $ 8.600,00

    RM = RTx

    RM = 1.000x 5x2 900x

    RM = 1.000 5x - 900x

    RM x=10 =1.000 5.10 90010

    RM x=10 = 1.000 50 90

    RM x=10 = $ 860,00

    4.) Se a curva de custo marginal dada por Cmg = 3x2 5x + 10 determinaro custo total e o custo mdio sabendo-se que o custo fixo associado 20.

    CT = CmgCT = (3x2 5x + 10) dxCT = 3x2 dx - 5x dx + 10 dx

    CT = 3x3 5x2 + 10x + c3 2

    CT = CF p/ x = 0

    20 = c

    CT = 3x3 5x2 + 10x + 203 2

    CT = x3 2,5x2 + 10x + 20

    CM = CTx

    CM = x3 2,5x2 + 10x + 20x

    CM = x2 2,5x + 10 + 20x