整式的乘法6题~1.x^2-y^2-x+y=(x-y)A,则A=.2.已知2^x=3,2^y=5,2^z=15.求证x+y=z.3.用你所学的知识,说明5^23-5^21能被120整除.4.设m^2+m-1=0,求m^3+2m^2+2004的值.5.若2x+5y-3=0,则4^x乘以32^y的值为多少?6.若3x(x^n+5)=3

Question

整式的乘法 6题~
1.x^2-y^2-x+y=(x-y)A,则A=_______.
2.已知2^x=3,2^y=5,2^z=15.求证x+y=z.
3.用你所学的知识,说明5^23-5^21能被120整除.
4.设m^2+m-1=0,求m^3+2m^2+2004的值.
5.若2x+5y-3=0,则4^x乘以32^y的值为多少?
6.若3x(x^n+5)=3x^n+1-7,则x=______.

Answer 1

1.x^2-y^2-x+y =(x+y)(x-y)-(x-y) =(x-y)(x+y-1) 所以A=x+y-1
2.(2^x)*(2^y)=15,同时(2^x)*(2^y)=2^(x+y)=15,所以 x+y=z.
3.5^23-5^21=5^21（5^2-1）=（5^21）*24,因为5*24=120,所以能被120整除
4.m^2+m-1=0 则m^2+m=1
m^3+2m^2-2004=m^3+m^2+m^2+2004 =m(m^2+m)+m^2+2004
=m^2+m+2004 =1+2004 =2005
5.4^x*32^y=2^2x*2^5y =2^(2x+5y) =2^3 =8
6.3x(x^n+5）=（3x^n+1）+15x=（3x^n+1）-7,所以x=-7/15.
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