数学计算题1、已知多项式3x的2次方+my-8与多项式-nx的2次方+2y+7的差中,不含x、y项,求n的m次方+mn的

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  • 1.3x的二次方+my-8-(-nx的平方+2y+7)

    =(3+n)x²+(m-2)y-15

    ∵不含有x,y

    ∴3+n=0

    m-2=0

    ∴m=2

    n=-3

    ∴n的m次方+m的n次方=9+1/8=73/8

    2.3ab-[2a-(2ab-2b)+3]

    =3ab-2a+(2ab-2b)-3

    =3ab-2a+2ab-2b-3

    =-2(a+b)+5ab-3

    =-2 x 4 + 5 x 3 -3

    =-8+15-3

    =4

    3.(x+2)²+丨y+1丨=0

    x+2=0 x=-2

    y+1=0 y=-1

    5xy²-{2x²y-[3xy²-(4xy²-2x²y)}

    =5xy²-[2x²y-(3xy²-4xy²+2x²y)]

    =5xy²-(2x²y+xy²-2x²y)

    =5xy²-xy²

    =4xy²

    =4*(-2)*(-1)²

    =-8

    4.(x²+ax-2y+7)-(bx²-2x+9y-1)

    =(1-b)x²+(a+2)x-11y+8

    根据题意得

    1-b=0,a+2=0

    ∴a=-2,b=1

    5.能

    原数【AB】= 10A + B

    新数【BA】= 10B + A

    和 = 10A+ B + 10B + A = 11A + 11B = 11(A + B)

    含因数11,必能被11整除.

    6.