Question

A=2-4+6-8+10-12+........+22-24+26

Answer 1

A=(-2)+(-2)+...+(-2)+26

=26-24=2

Answer 2

tìm A hay sao vậy bạn ?

Answer 3

Số hạng có là

\(\text{( 26 - 2) : 2 + 1 = 13 số}\)

\(\text{13 : 2 = 6 dư 1}\)

\(\text{=> A = 2-4+6-8+10-12+........+22-24+26}\)

\(\text{=> A = ( 2-4) + ( 6-8) + ( 10-12) + ... + ( 22-24) + 26}\)

\(\text{=> A = (-2) + (-2) + (-2) + ... + (-2) + ( -2) + 26 }\)

\(\text{=> A = (-2) x 6 + 26}\)

\(\text{=> A= -12 + 26}\)

\(\text{=> A = 14}\)