Question

[truc quynh]

Cho A = 1.2 + 2.3 + 3.4 + 4.5 + ..... + 100.101 
và B = 1.3 + 2.4 + 3.5 + 4.6 + .... + 100.102.
Vậy B - A = ........

(trinh bay ra)THANKS

Answer 1

[l҉o҉n҉g҉ d҉z҉]

Ta có : A = 1.2 + 2.3 + 3.4 + ...... + 100.101

=> 3A = 1.2.3 - 1.2.3 + 2.3.4 - 2.3.4 + ...... + 100.101.102

=> 3A = 100.101.102

=> A = 100.101.102/3

=> A = 343400

Answer 2

[Nguyễn Cát Uyên]

sai rồi