已知 Iab+2I +Ia+1I=0 求下式的值
____1___ ___1___ _______1_______
(a-1)(b+1) + (a-2)(b+2) +......+ (a-2005)(b+2005)
已知 Iab+2I +Ia+1I=0 求下式的值
____1___ ___1___ _______1_______
(a-1)(b+1) + (a-2)(b+2) +......+ (a-2005)(b+2005)
已知 Iab+2I +Ia+1I=0
a= -1,b=2
1/[(a-1)(b+1)]=[1/(a-1)]+[1/(b+1)]
代数就是 -1/2+1/3+(-1/3)+1/4+(-1/4)+1/5...........+(-1/2006)+1/2007= -1/2+1/2007= -2005/4014