Question

[Minh Khuất]

Bài 1 : Cho S1 = 1 + (-3) + 5 + (-7) + ..... + 17

S2 = -2 +4 + (-6) + 8 + .....+ (-18)

Tính S1 + S2

Answer 1

[Vị Thần Lang Thang]

S1+S2=(1-2-3+4)+(5-6-7+8)+(9-10-11+12)+(13-14-15+16)+17-18

= 0+0+0+0-1=-1

Answer 2

[Song Dongseok]

S1+S2=(1-2-3+4)+(5-6-7+8)+(9-10-11+12)+(13-14-15+16)+17-18

=0+0+0+0-1

=-1