答：1）lg2=a,lg3=blog12(5)=lg5 / lg12=lg(10/2) / lg(2*2*3)=(lg10-lg2) / (lg2+lg2+lg3)=(1-a) /(2a+b)2)log2(3)=a,log3(7)=b因为：log3(7)=log2(7)/log2(3)所以：b=log2(7)/a所以：ab=log2(7)log14(56)=log14(14...