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

Toán Lớp 8: 5x²-5/4x=0 (X-3)²-5.(3-x)=0 X²+3x-10=x+5

Tháng Tư 15, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: 5x²-5/4x=0
(X-3)²-5.(3-x)=0
X²+3x-10=x+5

Comments ( 2 )

  1. thuminhthong
    thuminhthong
    15 Tháng Tư, 2022 at 11:31 chiều
    Reply
    Gửi bạn:
    $1,\dfrac{5x^2-5}{4x}=0$ 
    $⇒5x^2-5=0$ 
    $⇒5(x^2-1)=0$ 
    $⇒5(x-1)(x+1)=0$ 
    $⇒$ $\left[\begin{matrix} x+1=0\\ x-1=0\end{matrix}\right.$
    $⇒$ $\left[\begin{matrix} x=-1\\ x=1\end{matrix}\right.$
    Vậy $x=±1$
    $2,(x-3)^2-5(3-x)=0$
    $⇒(x-3)^2+5(x-3)=0$
    $⇒(x-3)(x+2)=0$
    $⇒$ $\left[\begin{matrix} x-3=0\\ x+2=0\end{matrix}\right.$
    $⇒$ $\left[\begin{matrix} x=3\\ x=-2\end{matrix}\right.$
    Vậy $x=3$ hoặc $x=-2$
    $3,x^2+3x-10=x+5$
    $⇒x^2+3x-10-x-5=0$
    $⇒x^2-2x-15=0$
    $⇒x^2+3x-5x-15=0$
    $⇒x(x+3)-5(x+3)=0$
    $⇒(x-5)(x+3)=0$
    $⇒$ $\left[\begin{matrix} x-5=0\\ x+3=0\end{matrix}\right.$
    $⇒$ $\left[\begin{matrix} x=5\\ x=-3\end{matrix}\right.$
    Vậy $x=5$ hoặc $x=-3$

  2. tuminh25
    tuminh25
    15 Tháng Tư, 2022 at 11:31 chiều
    Reply
    Giải đáp:
    a, 5x^2 – 5/4x = 0
    <=> x.(5x – 5/4) = 0
    <=> $\left[\begin{matrix} x=0\\ 5x – \dfrac{5}{4} = 0\end{matrix}\right.$
    <=> $\left[\begin{matrix} x=0\\ x = \dfrac{1}{4} \end{matrix}\right.$
    Vậy x ∈ {0, 1/4}
    —————-
    b, (x – 3)^2 – 5.(3 – x) = 0
    <=> (x – 3)^2 + 5.(x – 3) = 0
    <=> (x – 3).[(x – 3) + 5] = 0
    <=> (3 – x).(x – 3 + 5) = 0
    <=> (3 -x).(x  + 2) = 0
    <=> $\left[\begin{matrix} 3 – x=0\\ x + 2 = 0\end{matrix}\right.$
    <=> $\left[\begin{matrix} x = 3\\ x  = -2\end{matrix}\right.$
    Vậy x ∈ {-2; 3}
    —————-
    c, x^2 + 3x – 10 = x + 5
    <=> x^2 + 3x – 10 – x –  5 = 0
    <=> x^2 + 2x – 15=  0
    <=> x^2 – 3x + 5x – 15 = 0
    <=> x.(x – 3) + 5.(x – 3) = 0
    <=> (x -3).(x + 5) = 0
    <=> $\left[\begin{matrix} x – 3\\ x + 5 = 0\end{matrix}\right.$
    <=> $\left[\begin{matrix} x = 3\\ x  = -5\end{matrix}\right.$
    Vậy x ∈ {-5; 3}
    ∘ dariana

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

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