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

Toán Lớp 8: 2x(2x-1)^2-3x(x-3)(x-3)-4x(x+1)^2

Toán Lớp 8: 2x(2x-1)^2-3x(x-3)(x-3)-4x(x+1)^2

Comments ( 2 )

  1. #huy
    Sửa đề :(x+3)(x-3)
    2x(2x-1)^2-3x(x+3)(x-3)-4x(x+1)^2
    =x[2(2x-1)^2-3(x+3)(x-3)-4(x+1)^2]
    =x.(8x^2-8x+2-3x^2+27-4x^2-8x-4)
    =x.(8x^2-3x^2-4x^2-8x-8x+2+27-4)
    =x(x^2-16x+25)
    =x^3-16x^2+25x
     

  2. Giải đáp:
    = x^3 + 2x^2 – 29x
    Lời giải và giải thích chi tiết:
    2x(2x-1)^2-3x(x-3)(x-3)-4x(x+1)^2
    = 2x[(2x)^2 – 2.2x.1 + 1^2] – 3x[(x-3)(x-3)] – 4x(x^2 + 2.x.1 + 1^2)
    = 2x(4x^2 – 4x + 1) – 3x(x^2 – 6x + 9) – 4x(x^2 + 2x + 1)
    = 8x^3 – 8x^2 + 2x – 3x^3 + 18x^2 – 27x – 4x^3 – 8x^2 – 4x
    = (8x^3 – 3x^3 – 4x^3) – (8x^2 – 18x^2 + 8x^2) + (2x – 27x – 4x)
    = x^3 – (- 2x^2) – 29x
    = x^3 + 2x^2 – 29x
    #SunHee

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