令a=2^x+1则2^(x+1)+2=2a所以log2(a)*log2(2a)=2log2(a)*[log2(2)+log2(a)]=2[log2(a)]²+log2(a)-2=0[log2(a)+2][log2(a)-1]=0log2(a)=-2,log2(a)=1a=1/4,a=22^x+1=1/42^x=-3/4