(m+2)^2-9(m-1)^2 (x-y)(x^2+xy+y^2)-xy(y-x)

2个回答

  • (m+2)^2-9(m-1)^2 平方差

    =[(m+2)-3(m-1)][(m+2)+3(m-1)]

    =(m+2-3m+3)(m+2+3m-3)

    =(5-2m)(4m-1)

    (x-y)(x^2+xy+y^2)-xy(y-x)提取公因式

    =(x-y)(x^2+xy+y^2)+xy(x-y)

    =(x-y)[(x^2+xy+y^2)+xy]

    =(x-y)(x^2+xy+y^2+xy)

    =(x-y)(x^2+2xy+y^2)完全平方公式

    =(x-y)(x+y)^2

    3(x-1)^2-18(x-1)+27 提取公因式

    =3[(x-1)^2-6(x-1)+9]完全平方公式

    =3(x-1-3)^2

    =3(x-4)^2

    9*1.2^2-16*1.4^2平方差

    =(3*1.2-4*1.4)(3*1.2+4*1.4)

    =(3.6-5.6)(3.6+5.6)

    =-2*9.2

    =-18.4