Question

[Phan Ngọc Anh]

1) Cho 

1/M=1/1+2+3+1/1+2+3+4+..+1/1+2+3+..+59

CMR M>2/3

2)Tính:

P=(1-1/111)(1-2/111)...(1-2009/111)

Answer 1

[Lê Bùi]

P=\(\left(1-\dfrac{1}{111}\right)\left(1-\dfrac{2}{111}\right)\times...\times\left(1-\dfrac{111}{111}\right)\times...\times\left(1-\dfrac{2009}{111}\right)\)

P=\(\left(1-\dfrac{1}{111}\right)\left(1-\dfrac{2}{111}\right)\times...\times0\times...\times\left(1-\dfrac{2009}{111}\right)\)

P=0