Question

cho s=1/11+1/12+1/13+1/14+1/15+1/16+1/17+1/18+1/19+1/20. hãy so sánh với 1/2

Answer 1

Ta có các phân số 1/11 ; 1/12 ; 1/13 ; 1/14 ; 1/15 ; 1/16 ; 1/17 ; 1/18 ; 1/19 đều lớn hơn 1/20

Do đó : 1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1/16 + 1/17 + 1/18 + 1/19 + 1/20 > 1/20 + 1/20 + ;...+ 1/20 ( có 10 phân số 1/20 )

1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1 /16 + 1/17 + 1/18 + 1/19 + 1/20 > 10/20

1/11 + 1/12 + 1/13 + 1/14 + 1/15 + 1 /16 + 1/17 + 1/18 + 1/19 + 1/20 > 1/2

Vậy : S > 1/2

Answer 2

S>\(\frac{1}{2}\)

Answer 3

s>1/2

Answer 4

s>1/2

Answer 5

S>1/2

Answer 6

Ta có:1/11>1/20;1/12>1/20;........;1/20=1/20

=>1/11+1/12+1/13+...+1/20>10/20=1/2

Vay 1/11+1/12+...+1/20>1/2

Answer 7

Em có thể tham khảo video:

https://www.youtube.com/watch?v=T60Nn28G6rg&list=PLq0mRSDfY0BAMTu98fNHi-Lg_E9BWDYhV&index=8

Answer 8

s<1/2

Answer 9

s>1/2

Answer 10

S lớn hơn 1/2