Question

若绝对值ab-2加绝对值b-1等于0,求1÷ab+1÷(a+1)(b+1)+1÷(a+2)(b+2)+.+1÷（a+20

Answer 1

ab-2=0,b-1=0

a=2,b=1

1/1*2+1/(3*2)+1/(4*3)+……+1/(2005*2004)

=(1-1/2)+(1/2-1/3)+……+(1/2004-1/2005)

=1-1/2005

=2004/2005