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

Toán Lớp 8: a)(x2-x)(x+1)+x b)(x-1)(x3+x2+x+1)

Toán Lớp 8: a)(x2-x)(x+1)+x
b)(x-1)(x3+x2+x+1)

Comments ( 2 )

  1. a) (x^2-x)(x+1)+x
    =x(x-1)(x+1)+x
    =x(x^2-1)+x
    =x^3-x+x
    =x^3
    b) (x-1)(x^3+x^2+x+1)
    =x^4+x^3+x^2+x-x^3-x^2-x-1
    =x^4+(x^3-x^3)+(x^2-x^2)+(x-x)-1
    =x^4-1
    #wcdi
     

  2. Giải đáp:
     $a) (x²-x).(x+1)+x$
    $= x³+x²-x²-x+x$
    $= x³+(x²-x²)+(x-x)$
    $= x³$
    $b) (x-1).(x³+x²+x+1)$
    $= x.(x³+x²+x+1)-1.(x³+x²+x+1)$
    $= x^4+x³+x²+x-x³-x²-x-1$
    $= x^4+(x³-x³)+(x²-x²)+(x-x)-1$
    $= x^4-1$
     

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

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