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

Toán Lớp 8: (-x).(x-y)=? (X-7)(x-5)=? (X-1)(x+1)(x+12)

Toán Lớp 8: (-x).(x-y)=?
(X-7)(x-5)=?
(X-1)(x+1)(x+12)

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
     (-x) . (x – y)
    = (-x) . x + x . y
    = -x^2 + xy = xy – x^2
     (x – 7)(x – 5)
    = x(x – 7) – 5(x – 7)
    = x^2 – 7x – 12x + 35
    = x^2 – 19x + 35
    (x – 1)(x + 1)(x + 12)
    = [ x(x + 1) – 1(x + 1)](x + 12)
    = ( x^2 + x – x – 1)(x + 12)
    = (x^2 – 1)(x + 12)
    = x^2(x + 12) – 1(x + 12)
    = x^3 + 12x^2 – x – 12

  2. $(-x).(x-y)=xy-x^{2}$
    $(x-7)(x-5)=x^2-12x+35^{}$
    $(x-1)(x+1)(x+12)=x^3+12x^2-x-12^{}$

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

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