Matematika

Pertanyaan

daerah D dikuadran 1 dibatasi oleh parabola x=1/2ypangkat 2 garis x-y=4 dan sumbu X . hitunglah luas daerah D

2 Jawaban

  • 2 per 2 - 4 ...............................................................
  • x - y = 4
    y = x - 4

    2x = y²
    2x = (x - 4)²
    2x = x² - 8x + 16
    x² - 8x - 2x + 16 = 0
    x² - 10x + 16 = 0
    (x  - 8)(x - 2) = 0
    x = 8    x = 2

    y = √2x 
    y = x - 4

    [tex] \int\limits^8_2 {(x - 4) - \sqrt{2x} } \, dx [/tex]
    [tex] \int\limits^8_2 {x - 4 - (2x) ^{1/2} } \, dx [/tex]
    [tex][ \frac{1}{2} x^{2} - 4x - \frac{2√2}{3} x^{3/2} ][/tex]
    [1/2(8)² - 4(8) - [tex] \frac{2√2}{3} (8)^{3/2} [/tex]] - [ 1/2(2)² - 4(2) - [tex] \frac{2√2}{3} (2)^{3/2} [/tex]
    [32 - 32 - (2√2)/3(16√2)] - [2 - 8 - (2√2/3)(2√2)]
    -32/3 + 6 + 16/3
    -16/3 + 18/3 = 2/3 satuan luas


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