1,(a^x*a^y)^z=[a^(x+y)]^10=a^[10(x+y)]=a^20
10(x+y)=20
x+y=2
2,x^3n＝4,y^2n＝3
x^6ny^4n=(x^3n)^2*(y^2n)^2=16*9=144
3,N＝2^12*5^8=2^4*2^8*5^8=16*(2*5)^8=16*10^8
10^8有9位
所以16*10^8有10位
4,[(2/3)^2006*1.5^2007}/(－1)^2008
=[(2/3)^2006*1.5^2006*1.5}/1
=(2/3*1.5)^2006*1.5
=1^2006*1.5
=1.5
5,3*9^m*27^m＝3^21
3*3^2m*3^3m=3^21
3^(1+2m+3m)=3^21
1+2m+3m=21
5m=20
m=4
6,4*16^n＝4^9
4*4^2n=4^(1+2n)=4^9
1+2n=9
n=4
n^3/n
=n^2
=16
7,(1）a^2＝a*a
a可以取任意實(shí)數(shù)
(2）a換成2的3次方
等式可以成立
(2^3)^2=(2^3)*(2^3)
8,x^m＝5,x^n＝3,m,n均為正整數(shù),且2m＞3n,
x^(2m-3n)
=x^2m/x^(3n)
=(x^m)^2/(x^n)^3
=5^2/3^3
=25/27