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

Toán Lớp 6: BÀi 4 :Tìm x biết : a) $\dfrac{x}{2}$ = $\dfrac{-2}{-x}$ b) $\dfrac{x-1}{5}$ = $\dfrac{5}{x-1}$

Home/ Toán Lớp 6: BÀi 4 :Tìm x biết : a) $\dfrac{x}{2}$ = $\dfrac{-2}{-x}$ b) $\dfrac{x-1}{5}$ = $\dfrac{5}{x-1}$

Toán Lớp 6: BÀi 4 :Tìm x biết : a) $\dfrac{x}{2}$ = $\dfrac{-2}{-x}$ b) $\dfrac{x-1}{5}$ = $\dfrac{5}{x-1}$

Tháng Hai 13, 2023 Toán học 2 Comments 0 views

Toán Lớp 6: BÀi 4 :Tìm x biết :
a) $\dfrac{x}{2}$ = $\dfrac{-2}{-x}$
b) $\dfrac{x-1}{5}$ = $\dfrac{5}{x-1}$

Comments ( 2 )

  1. kimnguenoanh
    kimnguenoanh
    13 Tháng Hai, 2023 at 12:30 sáng
    Reply
    a) x/2 = (-2)/(-x)
    => x/2 = 2/x
    => x^2 = 2 . 2
    => x^2 = 4
    => x^2 = (±2)^2
    => x = ±2
    b) (x – 1)/5 = 5/(x – 1)
    => (x – 1)^2 = 5 . 5
    => (x – 2)^2 = 25
    => (x – 2)^2 = (±5)^2
    => x – 2 in {5; -5}
    => x in {7; -3}

  2. cobebongdem
    cobebongdem
    13 Tháng Hai, 2023 at 12:30 sáng
    Reply
    (-2)/(-x) = 2/x
    => x/2 = 2/x
    x . x = 2 . 2
    x^2 = 4
    x^2 = (+-2)^2
    => \(\left[ \begin{array}{l}x = 2\\x = -2\end{array} \right.\) 
    Vậy: x ∈ {2; -2}
    b)
    (x – 1)/5 = 5/(x – 1)
    (x – 1) . (x – 1) = 5 . 5
    (x – 1)^2 = 25
    (x – 1)^2 = (+-5)^2
    => \(\left[ \begin{array}{l}x – 1 = 2\\x – 1 = -2\end{array} \right.\)
    => \(\left[ \begin{array}{l}x = 2 + 1\\x = -2 + 1\end{array} \right.\)
    => \(\left[ \begin{array}{l}x = 3\\x = -1\end{array} \right.\) 
    Vậy: x ∈ {3; -1}

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

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