k=2^6a = 3^2b = 6^2clgk=6alg2=2blg3=2clg6lg2=lgk/6alg3=lgk/2blg6=lgk/2clg2+lg3=lg6所以lgk/6a+lgk/2b=lgk/2c1/6a+1/2b=1/2c1/c=1/3a+1/b=(b+3a)/(3ab)c=3ab/(3a+b)