Question

F=1x2x3+2x3x4+...+98x99x100

tính tổng của dãy số

 

Answer 1

các bn giúp mk nha mk đang cần gấp

Answer 2

Ta có:

\(F=1.2.3+2.3.4+...+98.99.100\)

\(\Rightarrow4F=1.2.3.\left(4-0\right)+2.3.4.\left(5-1\right)+....+98.99.100.\left(101-97\right)\)

\(\Rightarrow4F=1.2.3.4+2.3.4.5-1.2.3.4+...+98.99.100.101-97.98.99.100\)

\(\Rightarrow4F=98.99.100.101\Leftrightarrow F=\frac{98.99.100.101}{4}=24497550\)

Answer 3

(98x(98+1)x(98+2)x(98+3))=24497550

Answer 4

(98X(98+1)x(98+2)x(98+34)):4=24497550mimh quen chua chia 4

Answer 5

thank you very much

Answer 6

bui thi ngoc thao mk ko thi violympic ma mk thi IOE bn nha