log(2)9 = 2log(2)3log(3)4= 2log(3)2=》4log(2)3 *log(3)2=> 4* (log(2)3*(1/(log(2)3)))=4//由换底公式 log(a)(b)=log(b)(b)/log(b)(a) ----取以b为底的对数,log(b)(b)=1  =1/log(b)(a)...谢谢咯太给力了，你的回答完美解决了我的问题！