If la-1l + lab-2l = 0, find the sum of 1 / AB + 1 / (a + 1) (B + 1) +... + 1 / (a + 2002) (B + 2003) A math problem in the top one year junior high school students' question bank

If la-1l + lab-2l = 0, find the sum of 1 / AB + 1 / (a + 1) (B + 1) +... + 1 / (a + 2002) (B + 2003) A math problem in the top one year junior high school students' question bank

I guess you got the wrong number in the end. The last item may be 1 / (a + 2002) (B + 2002)
a=1 b=2
Then we get 1 / (1 * 2) + 1 / (2 * 3) +... + 1 / (2003 * 2004)
It's easy to take apart
(1/1-1/2)+(1/2-1/3)+...+(1/2003-1/2004)=1-1/2004=2003/2004