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

Toán Lớp 8: Rút gọn: (x²-2) (1-x)+(x+3)(x²-3x+9)

Toán Lớp 8: Rút gọn: (x²-2) (1-x)+(x+3)(x²-3x+9)

Comments ( 2 )

  1. (x^2 – 2)(1-x) + (x+3)(x^2 – 3x + 9)
    =x^2(1-x) – 2(1-x) + (x+3)(x^2- 3.x. + 3^2)
    = x^2 – x^3 – 2 + 2x + x^3 + 3^3
    = (-x^3 + x^3) + x^2 + 2x + (3^3 – 2)
    = x^2 + 2x + 25

  2. Giải đáp:
     $(x²-2).(1-x)+(x+3).(x²-3x+9)$
    $= x²-x³-2+2x+x³+27$
    $= (x³-x³)+x²+2x+(27-2)$
    $= x²+2x+25$
    $\text{Áp dụng HĐT: A³+B³=(A+B).(A²-AB+B²)}$
    $\text{@anhnguyen}$
    $\text{#Hoidap247}$
     

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

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