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

Toán Lớp 8: (x+1) ³ -(x-1) ³ -6 (x-1)(x+1)

Toán Lớp 8: (x+1) ³ -(x-1) ³ -6 (x-1)(x+1)

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    (x+1)^3-(x-1)^3-6(x-1)(x+1)
    =x^3+3x^2+3x+1-x^3+3x^2-3x+1-6x^2+6
    =(x^3-x^3)+(3x^2+3x^2-6x^2)+(3x-3x)+(1+1+6)
    =8 

  2. Giải đáp:
     (x + 1)^3 – (x – 1)^3 – 6(x – 1)(x + 1)
    = x^3 + 3x^2 .1 + 3x.1^2 + 1^3 – (x^3 – 3x^2 . 1 + 3x.1^2 – 1^3) – 6(x^2 – 1^2)
    = x^3 + 3x^2  + 3x + 1 – (x^3 – 3x^2  + 3x – 1) – 6(x^2 – 1)
    = x^3 + 3x^2 + 3x + 1 – x^3 + 3x^2 – 3x +1 – 6x^2 + 6
    = (x^3 – x^3) + (3x^2 + 3x^2 – 6x^2) + (3x – 3x) + (1 + 1 + 6)
    =  8

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