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

Toán Lớp 8: (x+2)³ +x(x-x²) -(x +1)(7x +5)

Toán Lớp 8: (x+2)³ +x(x-x²) -(x +1)(7x +5)

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
       (x+2)^3+x(x-x^2)-(x+1)(7x+5)
    =x^3+3.x^2.2+3.x.2^2+2^3+x^2-x^3-(7x^2+5x+7x+5)
    =x^3+6x^2+12x+8+x^2-x^3-7x^2-5x-7x-5
    =(x^3-x^3)+(6x^2+x^2-7x^2)+(12x-5x-7x)+(8-5)
    =3

  2. Giải đáp:
     $(x+2)^3+x.(x-x^2)-(x+1).(7x+5)$
    $= x³+6x^2+12x+8+x^2-x^3-(7x^2+5x+7x+5)$
    $= x^3+6x^2+12x+8+x^2-x^3-7x²-12x-5$
    $= (x³-x^3)+(6x^2+x^2-7x^2)+(12x-12x)+(8-5)$
    $= 3$
     

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