a=lg3/lg2
lg3=alg2
是不是log3(5)=b?
b=lg5/lg3
lg5=blg3=ablg2
log36(45)
=lg45/lg36
=(2lg3+lg5)/(2lg2+2lg3)
=(2alg2+ablg2)/(2lg2+2alg2)
=(2a+ab)/(2+2a)