Toán Lớp 8: Tìm x biết a,(2x+5)^2+(4x+10)(3-x)+x^2-6x+9=0 b, (x-2)^2-(x-3)(x+2)=0 c,5x(x-2013)-2x+4026=0

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Toán Lớp 8:  Tìm x biết  a,(2x+5)^2+(4x+10)(3-x)+x^2-6x+9=0 b, (x-2)^2-(x-3)(x+2)=0 c,5x(x-2013)-2x+4026=0

landinhngoc97 · Answer

Giải đáp+Lời giải và giải thích chi tiết:   ${a) (2x+5)^2+(4x+10)(3-x)+x^2-6x+9=0}$   &hArr;${4x^2+20x+25+12x-4x^2+30-10x+x^2-6x+9=0}$   &hArr;${ x^2 +16x+64=0}$   &hArr;${(x+8)^2=0}$   &hArr;${x+8=0}$   &hArr;${x=-8}$   ${b) (x-2)^2-(x-3)(x+2)=0}$   ${b) (x^2-4x+4-(x^2+2x-3x-6)=0}$   ${b) (x^2-4x+4-x^2-2x+3x+6)=0}$   ${b) -3x+10=0}$   ${b) -3x=-10}$   ${b) x= }$$ frac{-10}{-3}$   ${b)x= }$$ frac{10}{3}$   ${c) 5x(x-2013)-2x+4026=0}$   ${c) 5x(x-2013)-2(x-2013)=0}$   ${c) (x-2013)(5x-2)=0}$    ( left[  begin{array}{l}x-2013=0  5x-2=0 end{array}  right. ) &hArr; ( left[  begin{array}{l}x=2013  5x=2 end{array}  right. )&hArr; ( left[  begin{array}{l}x=2013  x= frac{2}{5}  end{array}  right. )