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

Toán Lớp 8: Rút gọn: a) [(3x – 2)(x + 1) – (2x + 5)(x² – 1)] : (x + 1) b) (2x + 1)² – 2(2x +1)(3 – x) + (3 – x)²

Toán Lớp 8: Rút gọn:
a) [(3x – 2)(x + 1) – (2x + 5)(x² – 1)] : (x + 1)
b) (2x + 1)² – 2(2x +1)(3 – x) + (3 – x)²

Comments ( 2 )

  1. a) [(3x-2)(x+1)-(2x+5)(x^2-1)]:(x+1)
    =[3x^2+ 3x- 2x- 2-(2x^3- 2x+ 5x^2-5)]:(x+1)
    = (3x^2+ 3x- 2x- 2- 2x^3+ 2x- 5x^2+ 5):(x+1)
    = (-2x^2+ 3x+3- 2x^3):(x+1)
    = [-2x^2+ x(3-2x^2)+3]:(x+1)
    = [(3-2x^2)(1+x)]:(x+1)
    = 3- 2x^2
    —————-
    b) (2x+ 1)^2- 2(2x+1)(3-x)+(3-x)^2
    = 4x^2+ 4x+1+(-4x-2)(3-x)+9- 6x+ x^2
    = 4x^2+ 4x+ 1- 12x+ 4x^2- 6+ 2x+9- 6x+ x^2
    = 9x^2- 12x+4
     

  2. Đáp án:
     
    Giải thích các bước giải:
     

    toan-lop-8-rut-gon-a-3-2-1-2-5-1-1-b-2-1-2-2-1-3-3

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