\(2E=\frac{6}{1.3.5}+\frac{6}{3.5.7}+...+\frac{3}{13.15.17}\)
\(2E=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{13.15}-\frac{1}{15.17}\)
\(2E=\frac{1}{1.3}-\frac{1}{15.17}\)
\(2E=\frac{1}{15}-\frac{1}{255}\)
\(\Rightarrow2E=\frac{16}{255}\)
\(\Rightarrow E=\frac{8}{255}\)
Tính:
\(\frac{1.3.5...\left(2n-1\right)}{\left(n+1\right).\left(n+2\right).\left(n+3\right)...2n}\)
Tính :
\(D=\frac{\left(\frac{3}{10}-\frac{4}{5}-\frac{7}{20}\right).\frac{-5}{19}}{\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\frac{4}{3}}\)
\(E=\frac{1-\frac{1}{3}+\frac{1}{1+\frac{1}{3}}}{1-\frac{1}{3}-\frac{1}{1\frac{1}{3}}}\)
\(G=1-\frac{1}{1-\frac{2}{1-\frac{3}{1-\frac{1}{4}}}}\)
Thực hiện phép tính
a)\(16\frac{2}{7}:\left(\frac{-3}{5}\right)+28\frac{2}{7}:\frac{3}{5}\)
b)\(\left(2^2:\frac{4}{3}-\frac{1}{2}\right).\frac{6}{5}-17\)
c)\(\left(\frac{1}{3}\right)^{50}.\left(-9\right)^{25}-\frac{2}{3}:4\)
d)\(\frac{3}{5}:\left(\frac{-1}{15}-\frac{1}{6}\right)+\frac{3}{5}:\left(\frac{-1}{3}-1\frac{1}{15}\right)\)
e)\(\left(-6,5\right).5,7+5,7.\left(-3,5\right)\)
Giúp mik nka
Bài 1: Tính giá trị của biểu thức ( hợp lí nếu có thể)
a/ |-10| : (-2): (-5)+(-3)2
b/ 1+ (-2) +3 +(-4) + 5+ (-6)+....+ 21 (-22)
c/ \(\frac{3}{4}.\frac{5}{9}+\frac{3}{4}.\frac{4}{9}\)
d/ \(\frac{-4}{17}+\frac{5}{19}+\frac{-13}{17}+\frac{14}{19}+\frac{3}{115}\)
e/ \(\left(\frac{3}{4}+\frac{-7}{2}\right).\left(\frac{10}{11}+\frac{2}{22}\right)\)
Thanks. Nhanh hộ mik
Tính:
a) \(\left(\frac{3}{7}+\frac{1}{2}\right)^2\)
b) \(\left(\frac{3}{4}-\frac{5}{6}\right)^2\)
c) \(\frac{5^4.20^4}{25^5.4^5}\)
d) \(\left(\frac{-10}{3}\right)^5.\left(\frac{-6}{5}\right)^4\)
e) \(\left(1+\frac{2}{3}-\frac{1}{4}\right).\left(\frac{4}{5}-\frac{3}{4}\right)^2\)
f) \(2:\left(\frac{1}{2}-\frac{2}{3}\right)^3\)
CMR : E = \(1-\frac{1}{2^2}-\frac{1}{3^2}-...-\frac{1}{2004^2}>\frac{1}{2004}\)
F = \(\frac{1}{2^2}+\frac{1}{4^2}+...+\frac{1}{200^2}< \frac{1}{2}\)
H = \(\frac{1}{3}+\frac{2}{3^2}+\frac{3}{3^3}+...+\frac{100}{3^{100}}< \frac{3}{4}\)
m.n giúp mk mấy câu vio 7 với:
1)Cho \(D=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+......+\frac{10}{1400}\)
\(E=\frac{1}{1+2}+\frac{1}{1+2+3}+......+\frac{1}{1+2+3+....+24}\)
Tính tỉ số D/E?
2)Giả sử \(\frac{a+b}{a+c}=\frac{a-b}{a-c}\) và a khác c;a khác -c;ac khác 0
Tính giá trị biểu thức \(A=\frac{10b^2+9bc+c^2}{2b^2+bc+2c^2}\)
\(\frac{\frac{3}{8}-\frac{3}{10}+\frac{3}{11}+\frac{3}{12}}{\frac{-5}{8}+\frac{5}{10}-\frac{5}{11}-\frac{5}{12}}\)
Tính
Tính giá trị biểu thức:
\(A=\frac{0,125-\frac{1}{5}+\frac{1}{7}}{0,375-\frac{3}{5}+\frac{3}{7}}+\frac{\frac{1}{2}+\frac{1}{3}-0,2}{\frac{3}{4}+0,5-\frac{3}{10}}\)
