Question

[Trịnh hiếu anh]

tính hợp lí:

a 2.53.12+4.6.87-3.8.40

b C=4/5.7+4/7.9+...+4/59.61

c B=1.2+2.3+3.4+...+99.100

d E=1.2+3.4+5.6+...+99.100

F=1.4+2.5+3.6+....+97.100