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

Toán Lớp 7: : Tìm x biết: a) 6x^2 – 4x = 0 b) x^2 – 4 = 8(x – 2)

Tháng Bảy 12, 2022 Toán học 1 Comment 0 views

Toán Lớp 7: : Tìm x biết:
a) 6x^2 – 4x = 0
b) x^2 – 4 = 8(x – 2)

Comments ( 1 )

  1. quynhthanhnghi
    quynhthanhnghi
    12 Tháng Bảy, 2022 at 6:47 sáng
    Reply
    ~ Bạn tham khảo ~
    a, 6x^2 – 4x = 0
    <=> 2x(3x-2) = 0
    \(⇔\left[ \begin{array}{l}2x=0\\3x-2=0\end{array} \right.\) 
    \(⇔\left[ \begin{array}{l}x=0\\x=\dfrac23\end{array} \right.\) 
    Vậy x={0;2/3}
    b, x^2 – 4 = 8(x-2)
    <=> x^2 – 4 – 8x + 16 = 0
    <=> x^2 – 8x + 12 = 0
    <=> x^2 – 6x – 2x + 12 = 0
    <=> x(x-6) – 2(x-6) = 0
    <=> (x-6)(x-2)=0
    <=> [(x-6=0),(x-2=0):}
    <=> [(x=6),(x=2):}
    Vậy x={6;2}

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

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