设f(x)=ax²+bx+c f(x+1)+f(x-1) =2ax²+2bx+2a+2c

问题描述:

设f(x)=ax²+bx+c f(x+1)+f(x-1) =2ax²+2bx+2a+2c

f(x)=ax²+bx+c
故:f(x+1)+f(x-1)
=a(x+1)²+b(x+1)+c +a(x-1)²+b(x-1)+c
=2ax²+2bx+2a+2c