Matematika

Pertanyaan

Luas daerah yanv dibatasi olrh parabola y=-x²+1 dan y=x²+1 adalah.....

Mohon dibantu ya

2 Jawaban

  • [tex]\displaystyle y=y\\-x^2+1=x^2+1\\2x^2=0\\x=0\\\\L=\int\limits^{x_2}_{x_1}y_1-y_2\,dx\\L=\int\limits^{0}_{0}x^2+1+x^2-1\,dx\\L=\int\limits^{0}_{0}2x^2\,dx\\L=\left\frac23x^3\right|^{0}_{0}\\L=\frac23(0)^3-\frac23(0)^3\\\boxed{\boxed{L=0}}[/tex]
  • y2 - y1 = (x^2 - 1) - (-x^2 + 1) = 2x^2 - 2
    D = b^2 - 4ac = (0)^2 - 4(2)(-2) = 16
    Luas = D√D / 6a^2 = 16√16 / 6(2)^2 = 16 . 4 / 6 . 4 = 16/6 = 8/3 = 2 2/3

    Cara integral
    Titik potong : y = y
    => x^2 - 1 = -x^2 + 1
    => 2x^2 = 2
    => x^2 = 1
    => x = ± 1 jadi x = 1 atau x = -1
    Luas = integral (-x^2 + 1) - (x^2 - 1) dx
    = Integral (-2x^2 + 2) dx
    = -2/3 x^3 + 2x | batas -1 sampai 1
    = (-2/3 (1)^3 + 2(1)) - (-2/3 (-1)^3 + 2(-1))
    = (-2/3 + 2) - (2/3 - 2)
    = -4/3 + 4
    = (-4 + 12)/3
    = 8/3
    = 2 2/3

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