Các câu hỏi tương tự
TÍNH TỔNG:
\(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+\frac{1}{3\cdot4\cdot5}+.....+\frac{1}{n\left(n+1\right)\left(n+2\right)}\)
rút gọn \(B=\frac{5}{1\cdot2\cdot3}+\frac{5}{2\cdot3\cdot4}+....+\frac{5}{n\cdot\left(n+1\right)\left(n+2\right)}\)
Tính tổng của B :B=\(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+\frac{1}{3\cdot4\cdot5}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)}\)
HD:\(\frac{1}{k\left(k+1\right)\left(k+2\right)}=\frac{1}{2}\left(\frac{1}{k}+\frac{1}{k+2}\right)-\frac{1}{k+1}\)
(\(\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+.......+\frac{1}{9\cdot10}\right)\left(x-1\right)+\frac{1}{10}x=x-\frac{9}{10}\)
Tính:Afrac{1}{1cdot2cdot3}+frac{1}{2cdot3cdot4}+frac{1}{3cdot4cdot5}+...+frac{1}{48cdot49cdot50}Bleft(1-frac{1}{2}right)+left(1-frac{1}{4}right)+left(1-frac{1}{8}right)+...+left(1-frac{1}{1024}right)C4cdot5^{100}left(frac{1}{5}+frac{1}{5^2}+frac{1}{5^3}+...+frac{1}{5^{100}}right)D1+frac{9}{45}+frac{9}{105}+frac{9}{189}+frac{9}{29997}Không cần làm hết cũng đc, giúp tớ nha
Đọc tiếp
Tính:
A=\(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+\frac{1}{3\cdot4\cdot5}+...+\frac{1}{48\cdot49\cdot50}\)
B=\(\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{4}\right)+\left(1-\frac{1}{8}\right)+...+\left(1-\frac{1}{1024}\right)\)
C=\(4\cdot5^{100}\left(\frac{1}{5}+\frac{1}{5^2}+\frac{1}{5^3}+...+\frac{1}{5^{100}}\right)\)
D=\(1+\frac{9}{45}+\frac{9}{105}+\frac{9}{189}+\frac{9}{29997}\)
Không cần làm hết cũng đc, giúp tớ nha
\(\frac{1}{1\cdot2\cdot3\cdot4}+\frac{1}{2\cdot3\cdot4\cdot5}+...+\frac{1}{2011\cdot2012\cdot2013\cdot2014}\)
rút gọn \(A=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+...+\frac{1}{\left(n-1\right)n}\)
\(P=\frac{1}{1\cdot2\cdot3\cdot\text{4}}+\frac{1}{2\cdot3\cdot4\cdot5}+.........+\frac{1}{102\cdot103\cdot104\cdot105}\)
Tính Tổng :
\(A=\frac{1}{1\cdot2\cdot3\cdot4}+\frac{1}{2\cdot3\cdot4\cdot5}+\frac{1}{3\cdot4\cdot5\cdot6}+...+\frac{1}{47\cdot48\cdot49\cdot50}\) mọi người giúp em với ạ