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

Toán Lớp 8: Làm tính nhân: a) (x^2 – 2x+1)(x-1) b ( x^3 – 2x^2 +x -1)(5-x) Làm tính nhân: A ) ( x^2y^2 – 1/2+2y)(x-2y) B) x^2 -xy+y2)(x+y)

Toán Lớp 8: Làm tính nhân:
a) (x^2 – 2x+1)(x-1)
b ( x^3 – 2x^2 +x -1)(5-x)
Làm tính nhân:
A ) ( x^2y^2 – 1/2+2y)(x-2y)
B) x^2 -xy+y2)(x+y)

Comments ( 1 )

  1. a)(x^2-2x+1)(x-1)
    =x^3-x^2-2x^2+2x+x-1
    =x^3-(x^2+2x^2)+(2x+x)-1
    =x^3-3x^2+3x-1
    b)(x^3-2x^2+x-1)(5-x)
    =5x^3-x^4-10x^2+2x^3-x^2+5x+x-5
    =(5x^3+2x^3)-x^4-(10x^2+x^2)+(5x+x)-5
    =-x^4+7x^3-11x^2+6x-5
    __
    a)(x^2y^2-1/2+2y)(x-2y)
    =x^3y^2-2x^2y^3+1/2x-y+2xy-4y^2
    b)(x^2-xy+y^2)(x+y)
    =x^3+x^2y-x^2y-xy^2+xy^2+y^3
    =x^3+(x^2y-x^2y)-(xy^1-xy^1)+y^3
    =x^3+y^3

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

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