5/6-b+b^2/3=(1/3)(b-3/2)^2+1/12,设x=6^a,则x>0,36^(a+1)=36x^2,
∴原式x/(36x+1)用证明法怎么证啊？<==>这是什么意思？"<==>"读作“等价于".上面是分析法证明。∴原式<==>x/(36x+1)<=1/12这一步是怎么来的？