已知|AB+2|+|A+1=0,求:1/(A-1)(B+3)+1/(A-2)(B+3)+.1/(A-2008)(B+3)
问题描述:
已知|AB+2|+|A+1=0,求:1/(A-1)(B+3)+1/(A-2)(B+3)+.1/(A-2008)(B+3)
答
A=-1 B=2 =-1/5(1/2+1/3+.+1/2009) =-1/5*1005/2009 =-501/2009