1/2*3+1/3*4+1/4*5 + 1/5*6 + .... + 1/99 * 100
= 1/2 -1/3 + 1/3 - 1/4 + 1/4 - 1/5 + 1/5 - 1/6 +..... + 1/99 - 1/100
= 1/2 - 1/100
= 49/100 nha bạn !
1/2x3+1/3x4+1/4x5+1/5x6+....+1/99x100
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+....+1/99-1/100
=1/2-1/100=49/100
1/2*3+1/3*4+1/4*5 + 1/5*6 + .... + 1/99 * 100
= 1/2 -1/3 + 1/3 - 1/4 + 1/4 - 1/5 + 1/5 - 1/6 +..... + 1/99 - 1/100
= 1/2 - 1/100
= 49/100
Đúng rồi nha bạn !
= 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/99 - 1/100
= 1/2 - 1/100
= 49/100
Chuẩn 100% nha
1/2 x 3 + 1/3 x 4 + 1/4 x 5 + 1/5 x 6 + ..... + 1/99 x 100
= 1/2 x 1/3 + 1/3 x 1/4 + 1/4 x 1/5 + 1/5 x 1/6 + ..... + 1/99 x 1/100
1/3 x 1/4 + 1/4 x 1/5 + 1/5 x 1/6 + ...... + 1/99 ( Cái gạch ngang này là rút gọn đấy nhé )
= 1/2 - 1/100
= 49/100
Ta thấy : \(\frac{1}{2.3}=\frac{1}{2}-\frac{1}{3}\)
\(\frac{1}{3.4}=\frac{1}{3}-\frac{1}{4}\); .......; \(\frac{1}{99.100}=\frac{1}{99}-\frac{1}{100}\)
=> 1/ 2 *3 + 1/3*4 + 1/4*5 + 1/5*6 + ....+ 1/ 99 * 100
= \(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+......+\frac{1}{99}-\frac{1}{100}\)
= \(\frac{1}{2}-\frac{1}{100}\)
= \(\frac{49}{100}\)
Victor Nobita - kun kick cậu rồi đấy kick lại mk đi
