因为乘方在百度问题中显示不出来,所以将我的题目打在空间里,不过麻烦大家写在此页中,写在空间加不成分哦^^.还有一定要写过程,

Question

因为乘方在百度问题中显示不出来,所以将我的题目打在空间里,不过麻烦大家写在此页中,写在空间加不成分哦^_^.还有一定要写过程,

Answer 1

x+4y=3
2^x*16^y
=2^x*(2^4)^y
=2^x*2^4y
=2^(x+4y)
=2^3
=8
3^m=6,9^n=(3^2)n=3^2n=2
3^(2m-4n+1)
=[3^(m-2n)]^2*3^1
=(3^m/3^2n)^2*3
=(6/2)^2*3
=27
3^x+3^-x=2
两边平方
3^2x+2+3^(-2)=4
9^x+2+9^-x=4
9^x+9^-x=2
(x+y)^2=9
(x-y)^2=5
相减
(x+y)^2-(x-y)^2
=(x+y+x-y)(x+y-y+y)
=2x*2y
=4xy=9-5
所以xy=1
m^2+8m-1=0
m^2-8m=1
(1-m)(1+m)+(m-2)^2-2(m+3)^2
=1-m^2+m^2-4m+4-2m^2-12m-18
=-2m^2-16m-13
=-2(m^2+8m)-13
=-2-13
=-15