Question

[NguyenNgocThaoNguyen]

1/1x2 +1/2x3+1/3x4 +...........+1/99x100

Xin cac ban hay giup to tai vi chieu nay to phai di hoc them [thu bay,ngay 26/5]

Xin hay giup to

Answer 1

[Phùng Minh Quân]

~ Ko có đề bài -_- ~ 

Ta có : 

\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)

\(=\)\(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

\(=\)\(1-\frac{1}{100}\)

\(=\)\(\frac{99}{100}\)

Chúc bạn học tốt ~ 

Answer 2

[Kiên-Messi-8A-Boy2k6]

\(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+...+\frac{1}{99x100}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

\(=1-\frac{1}{100}\)

\(=\frac{99}{100}\)