写错了吧,lg√3前面有个2
原式=(1/2*lg2+2*1/2*lg3-1/2)/(lg18-lg10)
=(1/2*lg2+lg3-1/2)/(lg3²*2-lg10)
=1/2*(lg2+2lg3-1)/(lg2+2lg3-1)
=1/2