设a、b、c都是正数，且3^a = 4^b = 6^c 则：A. 1/c = 1/a + 1/b B. 2/c = 2/a + 1/b C. 1/c = 2/a + 2/b D. 2/c = 1/a + 2/b 哪位高手告诉我怎么摆平啊？要有过程啊，穷举不算。
热心网友
设a、b、c都是正数，且3^a = 4^b = 6^c 则：3^a = 4^b = 6^c=xlgx=alg3=2blg2=c(lg2+lg3)lg3=lgx/lgalg2=lgx/(2b)lg3+lg2=lgx/(c)=lgx/a+lgx/(2b)∴1/c=1/a+2/b 选C