(1)4^x=2^2x=(2^x)^2
2^(x+2)=2^x*2^2=4*2^x
即(2^x)^2<=4*2^x
整理得到(2^x-2)^2<=4
即-2<=2^x-2<=2
即0<=2^x<=4
解得x<=2
(2)lnx>0
lnx>ln1
x>1