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 nhanh\(A=1+\frac{1}{2}\times\left(1+2\right)+\frac{1}{3}\times\left(1+2+3\right)+\frac{1}{4}\times\left(1+2+3+4\right)+...+\frac{1}{16}\times\left(1+2+...+16\right)\)
E=\(1+\frac{1}{2}\times\left(1+2\right)+\frac{1}{3}\times\left(1+2+3\right)\frac{1}{4}\times\left(1+2+3+\right)+....+\frac{1}{200}\times\left(1+2+3+....+2001\right)\)
tính các tích sau
\(a=\frac{3}{4}\times\frac{8}{9}\times\frac{15}{16}\times...\times\frac{9999}{10000}\)
\(b=\left(1-\frac{1}{4}\right)\times\left(1-\frac{1}{9}\right)\times...\times\left(1-\frac{1}{10000}\right)\)
\(c=\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times...\times\left(1-\frac{1}{1994}\right)\)
\(d=\left(1+\frac{1}{1\times3}\right)\times\left(1+\frac{1}{2\times4}\right)\times\left(1+\frac{1}{3\times5}\right)\times...\times\left(1+\frac{1}{99\times100}\right)\)
Tinh\(\left(1-\frac{1}{1+2}\right)\times\left(1-\frac{1}{1+2+3}\right)\times\left(1-\frac{1}{1+2+3+4}\right)\times...\times\left(1-\frac{1}{1+2+3+...+2015}\right)\)
\(\left(1-\frac{1}{2^2}\right)\times\left(1-\frac{1}{3^2}\right)\times\left(1-\frac{1}{4^2}\right)\times...\times\left(1-\frac{1}{10^2}\right)\)
BÀI 1:TÍNH
A=\(\frac{7^2}{7\times8}\times\frac{8^2}{8\times9}\times...\times\frac{11^2}{11\times12}\)
B=\(\left(1+\frac{1}{11}\right)\times\left(1+\frac{1}{12}\right)\times...\times\left(1+\frac{1}{15}\right)\)
C=\(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times...\times\left(1-\frac{1}{2010}\right)\)
D=\(\left(\frac{1}{2}-1\right)\times\left(\frac{1}{3}-1\right)\times\left(\frac{1}{4}-1\right)\times...\times\left(\frac{1}{2010}-1\right)\)
BÀI 2: Tìm phân số tối giản \(\frac{a}{b}\)nhỏ nhất (a,b thuộc N sao)để khi nhân \(\frac{a}{b}với\frac{55}{16}:\frac{25}{24}\)được tích là các số tự nhiên.
D=\(\left(\frac{1}{2^2}-1\right)\times\left(\frac{1}{3^2}-1\right)\times\left(\frac{1}{4^2}-1\right)\times...\times\left(\frac{1}{100^2}-1\right)\)
a/\(\left(1+2^4+2^8\right):\left(1+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^{10}+2^{11}\right)\)
b/\(\left(\frac{1}{2}-1\right)\times\left(\frac{1}{3}-1\right)\times\left(\frac{1}{4}-1\right)\times...\times\left(\frac{1}{2004}-1\right)\)
GIÚP MÌNH NHA CHIỀU MÌNH NỘP RỒI