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

Toán Lớp 7: (4x+1)^2-(2x+3)^2+5(x+2)^2+3(x-2)(x+2) = 500

Toán Lớp 7: (4x+1)^2-(2x+3)^2+5(x+2)^2+3(x-2)(x+2) = 500

Comments ( 1 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    (4x+1)^2-(2x+3)^2+5(x+2)^2+3(x-2)(x+2)=500
    =>16x^2+8x+1-(4x^2+12x+9)+5(x^2+4x+4)+3(x^2-4)=500
    =>16x^2+8x+1-4x^2-12x-9+5x^2+20x+20+3x^2-12=500
    =>(16x^2-4x^2+5x^2+3x^2)+(8x-12x+20x)+(1-9-12+20)=500
    =>20x^2+16x-500=0
    =>4(5x^2+4x-125)=0
    =>5x^2+4x-125=0
    =>5x^2+2.x.5. 2/5 +5. 4/25 -629/5=0
    =>5(x^2+2.x 2/5+4/25-629/25)=0
    =>(x+2/5)^2-629/25=0
    =>(x+2/5)^2=(+-\frac{\sqrt{629}}{5})^2
    =>x=+-\frac{\sqrt{629}}{5]-2/5

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