Question

已知lg9=a,10^b=5,用a,b表示以36为底45的对数

Answer 1

已知lg9=a,10^b=5

==>B=lg5

所以LOG(36,45)=LG(45)/LG(36)=(LG(5)+LG(9))/(LG(4)+LG(9))

=(A+B)/(2LG(2)+A)=(A+B)/(2(1-LG(5))+A)=(A+B)/(2-2B+A)