3^x+3^(1-x)=4
3^x+3/3^x=4
(3^x)^2-4*3^x=3=0
(3^x-1)(3^x-3)=0
3^x=1 3^x=3
x=0 x=1
2^2x-6·2^(x+1)+2^5=0
2^2x-12*2^x+32=0
(2^x-4)(2^x-8)=0
2^x-4=0 2^x-8=0
x=2 x=3
若x＞0,y＞0,且x^1/2·(x^1/2+y^1/2)=3y^1/2·(x^1/2+5y^1/2)
x+x^1/2y^1/2=3x^1/2y^1/2+15y
x-2x^1/2y^1/2-15y=0
(x^1/2-5y^1/2)(x^1/2+3y^1/2)=0
x^1/2=5y^1/2 x^1/2=-3y^1/2(不合题意,舍去）
x=25y
(2x+2(xy)^1/2+3y/(x-(xy)^1/2+y)
=(2*25y+2(25y*y)^1/2+3y/(25y-(25y*y)^1/2+y)
=(50y+10y+3y)/(25y-5y+y)
=63y/21y
=3