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

Toán Lớp 8: giúp đi, có 1 câu à, tính nhé (x+5)(x+3)(x-7)-(4×2-3x+7)(x-1)

Toán Lớp 8: giúp đi, có 1 câu à, tính nhé
(x+5)(x+3)(x-7)-(4×2-3x+7)(x-1)

Comments ( 2 )

  1. (x + 5) (x + 3) (x – 7) – (4x^2 – 3x + 7) (x – 1)
    = x^2 + 3x + 5x + 15 (x – 7) – (4x^3 – 4x^2 – 3x^2 + 3x + 7x – 7)
    = x^3 – 7x^2 + 3x^2 – 21x + 5x^2 – 35x + 15x -105 – 4x^3 + 4x^2 + 3x^2 – 3x – 7x + 7
    = (x^3 – 4x^3) + (- 7x^2 + 3x^2 + 5x^2 + 4x^2 + 3x^2) + (- 21x – 35x + 15x – 3x – 7x) + (-105 + 7)
    = – 3x^3 + 8x^2 – 51x – 98
    Bn xem lại đề chứ sao số ra không được đẹp lắm
     

  2. (x+5) (x+3) (x-7) – (4x^2-3x+7) (x-1)
    = (x^2+8x+15) (x-7) – (4x^3-7x^2+10x-7)
    = x^3 + x^2 – 41x – 105 – 4x^3 + 7x^2 – 10x + 7
    = – 3x^3 + 8x^2 – 51x – 98
     

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