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

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

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

Comments ( 2 )

  1. (x+2)(x^2 – 2x+4) – (x-2)^3
    = x^3 + 2^3 – (x-2)^3
    = x^3 + 8 – (x^3 – 3x^2 .2 + 3x.2^2 – 2^3)
    = x^3 +8 -(x^3 – 6x^2 + 12x -8)
    = x^3 +8 – x^3 + 6x^2 – 12x +8
    = 6x^2 – 12x + 16
     

  2. Giải đáp:
    = 6x^2 – 12x + 16
    Lời giải và giải thích chi tiết:
    ( x + 2 )( x^2 – 2x + 4 ) – (x – 2)^3
    = ( x + 2 )( x^2 – x.2 + 2^2) – (x^3 – 3.x^2 . 2 + 3.x.2^2 – 2^3)
    = (x^3 + 2^3) – (x^3 – 6x^2 + 12x – 8)
    = (x^3 + 8) – x^3 + 6x^2 – 12x + 8
    = x^3 + 8 – x^3 + 6x^2 – 12x + 8
    = (x^3 – x^3) + 6x^2 – 12x + (8 + 8)
    = 6x^2 – 12x + 16
    #SunHee

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