Ardışık Sayılar Sorusu

Question

A=1.3+2.4+3.5+...+88.90

B=1.2+2.3+3.4+...+88.89  ise A-B=?

Answer 1

A - B = 1.3+2.4+3.5+...+88.90 - (1.2+2.3+3.4+...+88.89) = 1.3+2.4+3.5+...+88.90 - 1.2-2.3-3.4-...-88.89

= 1(3 - 2) + 2(4 - 3) + 3(5 - 4) + ... + 88(90 - 89)

= 1 + 2 + 3 + ... + 88

= 88.89/2

= 3916