Question

tính

A=100+98+96+...+2-1-3-...-95-97

Answer 1

A=100+98+96+...+2-1-3-...-95-97

A=[(100+2).50:2]-[(97+1).49:2]

A=2550-2401

A=149

Answer 2

Ta có : A = 100 + 98 + 96 + .....+ 2 - 1 - 3 - .....- 95 - 97

A = (100 + 98 + 96 + .....+ 2 ) - ( 1 + 3 + .....+ 95 + 97)

A = [(100 + 2).50:2] - [(97+1).49:2]

A = 2550 - 2401 = 149

Vậy A = 149