[(lg3)^2-(lg2)^2]÷(lg9-lg4)
=(lg3+lg2)(lg3-lg2)÷(2lg3-2lg2)
=(lg3+lg2)(lg3-lg2)÷2(lg3-lg2)
=(lg3+lg2)/2
log下面是2上面是根号2=lg2^(1/2)/lg2=1/2
原式=(lg3+lg2)/2+1/2=1/2(1+lg6)=1/2(lg60)