1. So sanh

a) 42/43 va 58/59

b) 18/31 va 15/37

c) 53/57 va 531/571

d) 25/26 và 25251/26261

e) 3535.232323/353535.2323; 3535/3534 va 2323/2322

g) 13/38 va 1/3

2.Chung minh rang:

a) N=1/4^2+1/6^2+1/8^2+...+1/(2n)^2 < 1/4

b) 1/26+1/27+1/28+...+1/50=1-1/2+1/3-1/4+...+1/49-1/50

c) A=1/6+1/24+1/60+...+1/6840 < 1/4

d) B= 36/15+36/105+36/315+...+36/19575 < 3

Mn oi!!!!! Giup minh lam 2 bai nay voi!!!!!

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