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

Toán Lớp 8: Tìm x biết a, 3x(x-2)-x+2=0 b, 3x(x+5)-3x-15=0 c, (2x-1)^2-25=0

Toán Lớp 8: Tìm x biết
a, 3x(x-2)-x+2=0
b, 3x(x+5)-3x-15=0
c, (2x-1)^2-25=0

Comments ( 2 )

  1. a) 3x(x-2)-x+2=0
    <=>3x(x-2)-(x-2)=0
    <=>(x-2)(3x-1)=0
    <=>\(\left[ \begin{array}{l}x-2=0\\3x-1=0\end{array} \right.\) 
    <=>\(\left[ \begin{array}{l}x=2\\x=\dfrac{1}{3}\end{array} \right.\) 
    Vậy x=2 hoặc x=1/3
    b) 3x(x+5)-3x-15=0
    <=>3x(x+5)-(3x+15)=0
    <=>3x(x+5)-3(x+5)=0
    <=>3(x+5)(x-1)=0
    <=>\(\left[ \begin{array}{l}x+5=0\\x-1=0\end{array} \right.\) 
    <=>\(\left[ \begin{array}{l}x=-5\\x=1\end{array} \right.\) 
    Vậy x=-5 hoặc x=1
    c) (2x-1)^2-25=0
    <=>(2x-1-5)(2x-1+5)=0
    <=>(2x-6)(2x+4)=0
    <=>4(x-3)(x+2)=0
    <=>\(\left[ \begin{array}{l}x-3=0\\x+2=0\end{array} \right.\) 
    <=>\(\left[ \begin{array}{l}x=3\\x=-2\end{array} \right.\) 
    Vậy x=3 hoặc x=-2
     

  2. A chúc e học tốt và thành công trong cuộc sống nhé!
    toan-lop-8-tim-biet-a-3-2-2-0-b-3-5-3-15-0-c-2-1-2-25-0

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