已知函数f(x)满足f(xy)=f(x)+f(y),且f(2)=p,f(3)=q,求f(18)和f(72)的值.

问题描述:

已知函数f(x)满足f(xy)=f(x)+f(y),且f(2)=p,f(3)=q,求f(18)和f(72)的值.

∵f(xy)=f(x)+f(y)
∴f(6)=f(2)+f(3)=p+q,
∴f(18)=f(3)+f(6)=p+2q,
f(36)=f(6)+f(6)=2p+2q,
∴f(72)=f(36)+f(2)=3p+2q.