3^x=4^y=6^z
ln(3^x)=ln(4^y)=ln(6^z)
xln3=yln4=zln6
xln3=2yln2=z(ln2+ln3)
设xln3=2yln2=z(ln2+ln3)=t
ln3=t/x,ln2=t/(2y),ln2+ln3=t/z
t/(2y)+t/x=t/z
1/(2y)+1/x=1/z
1/z-1/x=1/(2y)