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

Toán Lớp 8: Tìm x 1)2x^2-6x=0 2)7x^2-28x=0 3)x(x-3)+x(1-x)=10 4)4(2x-1)-5(3+x)=x-25

Toán Lớp 8: Tìm x
1)2x^2-6x=0
2)7x^2-28x=0
3)x(x-3)+x(1-x)=10
4)4(2x-1)-5(3+x)=x-25

Comments ( 1 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
     1,2x^2 -6x=0
    =>2x(x-3)=0
    =>\(\left[ \begin{array}{l}2x=0\\x-3=0\end{array} \right.\) $\\$=>\(\left[ \begin{array}{l}x=0\\x=3\end{array} \right.\) 
    Vậy
    2,7x^2 -28x=0
    =>7x(x-4)=0
    =>\(\left[ \begin{array}{l}7x=0\\x-4=0\end{array} \right.\) $\\$=>\(\left[ \begin{array}{l}x=0\\x=4\end{array} \right.\) 
    Vậy
    3,x(x-3)+x(1-x)=0
    =>x^2 -3x+x-x^2 =0
    =>-2x=0
    =>x=0
    4,4(2x-1)-5(3+x)=x-25
    =>8x-4-15-5x-x=-25
    =>(8x-5x-x)+(-4-15)=-25
    =>2x-19=-25
    =>2x=-25+19
    =>2x=-6
    =>x=-3

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