已知log189=a,18b=5,用a,b表示log3645.

已知log189=a,18b=5,用a,b表示log3645.

∵18b=5,∴b=log185,又log189=a,∴log3645=log1845log1836=log189+log185log183249=a+blog18182−log189=a+b2−a.