计算1/a(a+1)+1/(a+1)(a+2)+1/(a+2)(a+3)+···+1/(a+2004)(a+2005)
(a+1)(a+2)(a-3)计算
计算a^3/a-1-a^2-a-1
计算 a^2/1+a+1-a
计算(a+1)(a+2)(a+3)(a-6)
(a 1)(a 2)(a 3)(a
计算2a(a-3)^1-6a^2(3-a)-8a(a-3)
计算:a+1/a-1+a-2/1-a
求和:1,a+a^2,a^3+a^4+a^5,a^6+a^7+a^8+a^9,···(a不等于0)
a(a-1)(a-2)(a-3)(a-4)因式分解
·(1-a)(1+a)(a^2+a+1)(a^2-a+1)=______________
计算1/a(a+1)+1/(a+1)(a+2)+...+1/(a+2007)(a+2008)
计算:1/a(a+1)+1/(a+1)(a+2)+...+1/(a+2006)(a+2007)