Tính tích :
B=\(\left(\frac{1}{1.2}-1\right)\left(\frac{1}{2.3}-1\right)\left(\frac{1}{3.4}-1\right).....\left(\frac{1}{99.100}-1\right)\)
A = \(\left(1-\frac{1}{1.2}\right)+\left(1-\frac{1}{2.3}\right)+...+\left(1-\frac{1}{2015.2016}\right)\)
\(\left(1-\frac{1}{1.2}\right).\left(1-\frac{1}{2.3}\right)....\left(1-\frac{1}{2009.2010}\right)\)Tính
Tính
A=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}\)
B=\(\left(1+\frac{1}{2}\right).\left(1+\frac{1}{3}\right).\left(1+\frac{1}{4}\right)...\left(1+\frac{1}{99}\right)\)
Tìm x, biết
\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{2}\right)=1\)
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2.\left(x+1\right)}=\frac{99}{100}\)
\(y=\frac{\left(-1-2-3-.......-50\right).\left(\frac{1}{3}-\frac{1}{5}-\frac{1}{7}-\frac{1}{9}\right).\left(6,3.12\right)-21.3,6}{\frac{1}{1.2}+\frac{1}{2.3}+......+\frac{1}{99.100}}\)
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2019.2020}=\frac{1}{x}\left(x\right)khác0\left(\right)\)
\(\frac{1^2}{1.2}.\frac{2^2}{2.3}.\frac{3^2}{3.4}......\frac{99^2}{99.100}\)
\(\left(1+\frac{1}{2}\right).\left(1+\frac{1}{3}\right).\left(1+\frac{1}{4}\right)......\left(1+\frac{1}{100}\right)\)
\(\left(\frac{1}{7}+\frac{1}{23}+\frac{1}{1009}\right):\left(\frac{1}{23}+\frac{1}{7}-\frac{1}{1009}+\frac{1}{7}.\frac{1}{23}.\frac{1}{1009}\right)+1:\left(30.1009-160\right)\)
đề bài tính nhanh
Tìm x biết: \(\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\right).\left(x-1\right)=x-\frac{1}{3}\)
