(1) (x+3)^2-(x-1)(x-2) (2)(a^2-1)除以(1-a分之1) (3)(x+y)^2-(x^3-

1个回答

  • (1) (x+3)^2-(x-1)(x-2)

    =x^2+6x+9-(x^2-3x+2)

    =x^2+6x+9-x^2+3x-2

    =x^2-x^2+6x+3x+9-2

    =9x+7

    (2)(a^2-1)÷(1-1/a)

    =(a^2-1)÷(a-1)/a

    =(a-1)(a+1)×a/(a-1)

    =a(a+1)

    =a^2+a

    (3)(x+y)^2-(x^3-y^3)除以(x-y)

    =(x+y)^2-(x-y)(x^2+xy+y^2)×1/(x-y)

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

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

    =xy

    {3x^2(a^2+b^2)-3a^2b^2+3[x^2+(a+b)x+ab]*[x(x-a)-b(x-a)]}除以2x^2

    ={3x^2(a^2+b^2)-3a^2b^2+3[(x+a)(x+b)]*[(x-b)(x-a)]}除以2x^2

    ={3x^2(a^2+b^2)-3a^2b^2+3[(x+a)(x-a)]*[(x-b)(x+b)]}除以2x^2

    ={3x^2(a^2+b^2)-3a^2b^2+3[(x^2-a^2)]*[(x^2-b^2)]}除以2x^2

    ={3x^2(a^2+b^2)-3a^2b^2+3[x^4-(a^2+b^2)x^2+a^2b^2]}除以2x^2

    ={3x^2(a^2+b^2)-3a^2b^2+3x^4-3(a^2+b^2)x^2+3a^2b^2]}除以2x^2

    =3x^4除以2x^2

    =3x^2/2

    =3*2^2/2

    =12/2

    =6