Question

Tinh tong :

A = 1/1*3 + 1/3*5 + 1/5*7 + ..... + 1/99*101

B = 1 + 1/3 + 1/6 + 1/10 + ..... + 1/630

Giup minh voi nha ! Ai dung minh *** cho !

Giai ro rang ho minh voi !

Answer 1

B = \(1+\frac{1}{3}+\frac{1}{6}+....+\frac{1}{630}=1+\frac{2}{6}+\frac{2}{12}+...+\frac{2}{1260}\)

B = \(1+2\left(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{35.36}\right)\)

B = \(1+2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{35}-\frac{1}{36}\right)\)

B = \(1+2\left(\frac{1}{2}-\frac{1}{36}\right)=1+2.\frac{17}{36}\)

B = \(1+\frac{17}{18}\)

B = \(\frac{35}{18}\)

Answer 2

\(A=\frac{1}{1x3}+\frac{1}{3x5}+\frac{1}{5x7}+...+\frac{1}{99x101}\)

\(A\)\(x2=\frac{2}{1x3}+\frac{2}{3x5}+\frac{2}{5x7}+...+\frac{2}{99x101}\)

\(A\)\(x2=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{99}-\frac{1}{101}\)

\(A\)\(x2=1-\frac{1}{101}=\frac{100}{101}\)

\(A=\frac{100}{101}:2=\frac{100}{101}x\frac{1}{2}=\frac{50}{101}\)

Answer 3

Haha ác quá mà

Answer 4

a ra 50/101 là dùng mình làm rùi

Answer 5

50/101 đấy bạn ạ

Answer 6

Tính A=1/1+3+1/1+3+5+...+1/1+3+5+...+2017.Mọi người giúp mình với ạ 

Answer 7

vvxc oooooooooooooooooooooooooooooo