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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Tìm x biết: x^2-9=0 4x^2-9=0 4x^2-36=0 x^3-16x=0 x^2+3x-10=0 3x^2+5x

Toán Lớp 8: Tìm x biết:
x^2-9=0 4x^2-9=0 4x^2-36=0
x^3-16x=0 x^2+3x-10=0 3x^2+5x+2=0

Comments ( 2 )

  1. #kehuydiet
    $x^2-9=0$
    $⇔ x=\pm 3$
    $4x^2-9=0$
    $⇔ 2x=\pm 3$
    $⇔ x=\pm \dfrac32$
    $4x^2-36=0$
    $⇔ 2x=\pm 6$
    $⇔ x\pm 3$
    $x^3-16x=0$
    $⇔ x(x^2-16)=0$
    $⇔ x=0$ hoặc $x=\pm 4$
    x^2+3x-10=0
    ⇔ x(x-2)+5(x-2)=0
    ⇔ (x+5)(x-2)=0
    $⇔ x=-5$ hoặc $x=2$
    $3x^2+5x+2=0$
    $⇔ 3x(x+1)+2(x+1)=0$
    $⇔ (3x+2)(x+1)=0$
    $⇔ x=-\dfrac23$ hoặc x=-1

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222-9+11+12:2*14+14 = ? ( )