f(x)除以(x-1)(x-2),余式为(2x+5),f(3)=5,求f(x)除以(x-1)(x-3) 的余式

问题描述:

f(x)除以(x-1)(x-2),余式为(2x+5),f(3)=5,求f(x)除以(x-1)(x-3) 的余式

C(x)是多项式
f(x)=C(x)*(x-1)(x-2)+2x+5
C(3)=5
f(x)/[(x-1)(x-3)]=C(x)*(x-2)/(x-3)+(2x+5)/[(x-1)(x-3)]
=C(x)*(x-2)/(x-3)+(2x-2+7)/[(x-1)(x-3)]
=[C(x)*(x-2)+2]/(x-3)+7/[(x-1)(x-3)]
因为x=3有意义
==>[C(x)*(x-2)+2]/(x-3)是多项式(能除净)
f(x)除以(x-1)(x-3) 的余式是 7