Question

E= 1/1.3+1/3.6+1/6.9+.........+1/20.23

dau cham la dau nhan

Answer 1

E=1/1.3+1/3.6+1/6.9+.............+1/20.23

<=>E=1/1-1/3+1/3-1/6+1/6-1/9+...........+1/20-1/23

<=>E=1/1-1/23

<=>E=22/23

Kb và k mk nha mn.

Answer 2

Cho hai phan so 1/n va 1/n+1 (n thuoc z)chung to rang h cua hai phan so nay bang hieu cua chung