1、若X+Y=6,x^2-y^2=24,则x-y的值是( )2、若m+n=3,则2M^2+4MN+2N^2-6的值为( )3、已知A=81^31,B=27^41,C=9^61,则A,B,C的大小关系?(用明天早上7点就要交的,悬赏分我回多给的!
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1、若X+Y=6,x^2-y^2=24,则x-y的值是( )
2、若m+n=3,则2M^2+4MN+2N^2-6的值为( )
3、已知A=81^31,B=27^41,C=9^61,则A,B,C的大小关系?(用
明天早上7点就要交的,悬赏分我回多给的!
1)
x²-y²=(x+y)(x-y)
6(x-y)=24
x-y=4
2)
2m²+4mn+2n²-6
=2(m+n)²-6
=2*9-6
=18-6
=12
3)
81^31
=(3^4)^31
=3^124
27^41
=(3^3)^41
=3^123
9^61
=(3^2)^61
=3^122
A>B>C
4)
=[(1+1/2)(1-1/2)]*[(1+1/3)(1-1/3)].*[(1+1/100)(1-1/100)]
=3/2*1/2*4/3*2/3*.*101/100*99/100
=1/2*101/100
=101/200
5)
2^12*5^8
=2^4*2^8*5^8
=2^4*10^8
=16*10^8
10位
1.x=5,y=1 x-y=4
2.2(m+n)^2-6=12
3.A=3^124,B=3^123,C=3^122..所以A>B>C
4.101/100
5.结果1600000000
1.x-y=4
1.x^2-y^2=(x-y)(x+y)所以x-y=4
2.2M^2+4MN+2N^2-6=2(m+n)^2-6=12
3.A=3^124 B=3^123 C=3^122 所以A>B>C
4.101/200
5.原式=10^8*2^4 所以答案是10
1用平方差
2用完全平方
3均化成底数为3 的幂
4用平方差
5化成10^8*2^4
这种题要自己练以后多着类
我只提供思路
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