Question

[Eric Võ]

Tính nhanh

\(B=\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{11}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}\)

Answer 1

[Nguyễn Lê Thanh Hà]

B=(1/5-1/5) + (-3/7+3/7) + (5/9-5/9) + (-2/11+2/11) + (7/13-7/13) - 9/16

  =     0       +       0       +      0      +         0         +      0         -  9/16

  =-9/16

Answer 2

[Nguyen Ngoc Ngan]

bằng -9/16