Question

Tính tổng S = 10.(\(\frac{1}{2.12}\)+\(\frac{1}{12.22}\)+\(\frac{1}{22.32}\)+\(\frac{1}{32.42}\)+.........+\(\frac{1}{2002.2012}\))

Answer 1

S=10/2.12+10/12.22+10/22.32+10/32.42+.......+10/2002.2012

S=1/2-1/12+1/12-1/22+1/22-1/32+1/32-1/42+.....+1/2002-1/2012

S=1/2-1/2012

S=????

bạn tự tính nhé

Answer 2

S=10.1/10{1/2-1/12+1/12-1/22+1/22-1/32+...+1/2002-1/2012}
  =1/2-1/2012
  =1005/2012