log5^25=b?b=2
已知条件应该是log(5)(2)=b?
lg代表以10为底数.
log(3)(10)=lg10/lg3=a=1/lg3 =>lg3=1/a
log(5)(2)=lg2/lg5=b =>lg2/(1-lg2)=b =>lg2=b/(1+b) lg5=1/(1+b)
log(4)(45)=lg45/lg4=(lg5+lg9)/(2lg2)=(lg5+2lg3)/(2lg2)=[1/(1+b)+2/a]/[2b/(1+b)]
=1/(2b)+b/[(1+b)a]