Các câu hỏi tương tự
Giá trị của tổng
A=\(\frac{3}{\left(1\cdot2\right)^2}\)+\(\frac{5}{\left(2\cdot3\right)^2}\)+\(\frac{7}{\left(3\cdot4\right)^2}\)+\(\frac{9}{\left(4\cdot5\right)^2}\)+......+\(\frac{89}{\left(44\cdot45\right)^2}\) là.....
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:\(\frac{1}{k\left(k+1\right)\left(k+2\right)}=\frac{1}{2}\left(\frac{1}{k}+\frac{1}{k+2}\right)-\frac{1}{k+1}\)
TÍNH TỔNG:
\(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+\frac{1}{3\cdot4\cdot5}+.....+\frac{1}{n\left(n+1\right)\left(n+2\right)}\)
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
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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
4Aleft(frac{1}{sqrt{25}+frac{1}{5}+1}right):left(frac{1}{25}-frac{1}{sqrt{25}-1}right)..Bfrac{1,5+0,left(3right)-0,1left(6right)}{2,5+1,left(6right)-0,8left(3right)}C1+7+7^2+.........+7^{50}5A-frac{1}{4}+frac{7}{3}+frac{3}{4}+frac{9}{2}-frac{5}{6}Bleft(-0,75-frac{1}{4}right):left(-5right)+frac{1}{15}-left(-frac{1}{5}:left(-3right)right)Cfrac{1}{1cdot2cdot3}+frac{1}{2cdot3cdot4}+.....+frac{1}{2015cdot2016cdot2017}CÁC BN HSG HÃY GIÚP EM 1 TÍ Ạ E KO NHỚ MẤY BÀI NÀY RA SAO Ạ
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4
\(A=\left(\frac{1}{\sqrt{25}+\frac{1}{5}+1}\right):\left(\frac{1}{25}-\frac{1}{\sqrt{25}-1}\right)..\)
\(B=\frac{1,5+0,\left(3\right)-0,1\left(6\right)}{2,5+1,\left(6\right)-0,8\left(3\right)}\)
\(C=1+7+7^2+.........+7^{50}\)
5
\(A=-\frac{1}{4}+\frac{7}{3}+\frac{3}{4}+\frac{9}{2}-\frac{5}{6}\)
\(B=\left(-0,75-\frac{1}{4}\right):\left(-5\right)+\frac{1}{15}-\left(-\frac{1}{5}:\left(-3\right)\right)\)
\(C=\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+.....+\frac{1}{2015\cdot2016\cdot2017}\)
CÁC BN HSG HÃY GIÚP EM 1 TÍ Ạ E KO NHỚ MẤY BÀI NÀY RA SAO Ạ
Giải phương trình:
\(\left(1+\frac{1}{1\cdot3}\right)\left(1+\frac{1}{2\cdot4}\right)\left(1+\frac{1}{3\cdot5}\right)...\left(1+\frac{1}{x\left(x+2\right)}\right)=\frac{1989}{995}\) 1989/995 nhé!!!
Cảm ơn mọi người
giải pt
\(\left(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+.......+\frac{1}{2005.2006.2007}\right)x=\left(1\cdot2+2\cdot3+.....+2006.2007\right)\)
rút gọn \(B=\frac{5}{1\cdot2\cdot3}+\frac{5}{2\cdot3\cdot4}+....+\frac{5}{n\cdot\left(n+1\right)\left(n+2\right)}\)
Rút gọn biểu thức : A= \(\frac{3}{\left(1\cdot2\right)^2}\) + \(\frac{5}{\left(2\cdot3\right)^2}\) + \(\frac{7}{\left(3\cdot4\right)^2}\) + .......+ \(\frac{2n+1}{\left[n\left(n+1\right)\right]^2}\)