Tìm tích:
1.\(\left(\frac{1}{2}+1\right)\times\left(\frac{1}{3}+1\right)\times\left(\frac{1}{4}+1\right)\times...\times\left(\frac{1}{999}+1\right)\)
2.\(\left(\frac{1}{2}-1\right)\times\left(\frac{1}{3}-1\right)\times\left(\frac{1}{4}-1\right)\times...\times\left(\frac{1}{1000}-1\right)\)
3.\(\frac{3}{2^2}\times\frac{8}{3^2}\times\frac{15}{4^2}\times...\times\frac{99}{10^2}\)
tính các tích sau
\(a=\frac{3}{4}\times\frac{8}{9}\times\frac{15}{16}\times...\times\frac{9999}{10000}\)
\(b=\left(1-\frac{1}{4}\right)\times\left(1-\frac{1}{9}\right)\times...\times\left(1-\frac{1}{10000}\right)\)
\(c=\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times...\times\left(1-\frac{1}{1994}\right)\)
\(d=\left(1+\frac{1}{1\times3}\right)\times\left(1+\frac{1}{2\times4}\right)\times\left(1+\frac{1}{3\times5}\right)\times...\times\left(1+\frac{1}{99\times100}\right)\)
\(\left(1-\frac{1}{2^2}\right)\times\left(1-\frac{1}{3^2}\right)\times\left(1-\frac{1}{4^2}\right)\times...\times\left(1-\frac{1}{10^2}\right)\)
D=\(\left(\frac{1}{2^2}-1\right)\times\left(\frac{1}{3^2}-1\right)\times\left(\frac{1}{4^2}-1\right)\times...\times\left(\frac{1}{100^2}-1\right)\)
E=\(1+\frac{1}{2}\times\left(1+2\right)+\frac{1}{3}\times\left(1+2+3\right)\frac{1}{4}\times\left(1+2+3+\right)+....+\frac{1}{200}\times\left(1+2+3+....+2001\right)\)
\(\left(\frac{1}{3}-1\right)\times\left(\frac{1}{6}-1\right)\times\left(\frac{1}{10}-1\right)\times\left(\frac{1}{15}-1\right)\times...\times\left(\frac{1}{1225}-1\right)\times\left(\frac{1}{1275}-1\right)\)=?
Tính: \(\left(1+\frac{1}{2}\right)\times\left(1+\frac{1}{3}\right)\times\left(1+\frac{1}{4}\right)\times...\times\left(1+\frac{1}{100}\right)\)
Tinh\(\left(1-\frac{1}{1+2}\right)\times\left(1-\frac{1}{1+2+3}\right)\times\left(1-\frac{1}{1+2+3+4}\right)\times...\times\left(1-\frac{1}{1+2+3+...+2015}\right)\)
\(\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{6}\right)\times\left(1-\frac{1}{10}\right)\times\left(1-\frac{1}{15}\right)\times...\times\left(1-\frac{1}{780}\right)\)