3+2√2=2+2√2+1=(√2+1)²而1/(√2+1)=(√2-1)/(√2+1)(√2-1)=(√2-1)/(2-1)=√2-1令a=√2+1则3+2√2=a²√2-1=1/a所以原式=log(1/a) a²用换底公式=lga²/lg(1/a)=2lga/(-lga)=-2
