log2 3=lg3/lg2=a,解得lg3=a*lg2.
log5 2=lg2/lg5=b,解得lg5=lg2/b.
log30 12=lg12/lg12=(lg3+2lg2)/(lg3+lg2+lg5)=(a+2)/(a+1+1/b)=(a+2)b/(ab+b+1).
log2 3=lg3/lg2=a,解得lg3=a*lg2.
log5 2=lg2/lg5=b,解得lg5=lg2/b.
log30 12=lg12/lg12=(lg3+2lg2)/(lg3+lg2+lg5)=(a+2)/(a+1+1/b)=(a+2)b/(ab+b+1).