3^a=4^b=6^calg3=blg4=clg6alg3=2blg2=c(lg2+lg3)(a-c)lg3=clg2 1)clg3=(2b-c)lg2 2)1)÷2）,得(a-c)/c=c/(2b-c)c^2=(a-c)(2b-c)=2ab-2bc-ac+c^2所以2ab-2bc-ac=0两边同时除以abc,得2/c-2/a-1/b=0即2/c=2/a+1/b...