\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{72}+\frac{1}{90}\)
=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+....+\frac{1}{8.9}+\frac{1}{9.10}\)
=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
=\(1-\frac{1}{10}=\frac{9}{10}\)
tính giá trị biểu thức : (\(\frac{-5}{6}\) + \(\frac{-5}{12}\) +\(\frac{-5}{20}\) + ...+\(\frac{-5}{90}\) ) : (0.25 +\(\frac{7}{6}\) - \(2\frac{1}{3}\) ) : \(\frac{24}{33}\)
Bài 1: Tính giá trị biểu thức:
\(A=\frac{4}{3}+\frac{4}{15}+\frac{4}{35}+...+\frac{4}{9999}\)
Bài 2: Cho \(B=\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{9^2}\)
Chứng tỏ: \(\frac{2}{5}< B=\frac{8}{9}\)
Bài 3: Tính giá trị biểu thức:
\(C=\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-\frac{1}{20}-...-\frac{1}{9900}\)
a, \(\left(12-\frac{7}{18}-10\frac{13}{18}\right):x-1\frac{7}{13}=1\frac{2}{3}\)
b,\(\left[\left(6\frac{3}{7}-\frac{0,75x-2}{0,35}\right).2,8+1,75\right]:0,05=235\)
c.\(\frac{3-x}{5-x}=\left(\frac{3}{5}\right)^2\)
d,\(\left(1-\frac{3}{10}-x\right):\left(\frac{19}{10}-1-\frac{2}{5}\right)+\frac{4}{5}=1\)
e,\(\left(12\frac{7}{18}-10\frac{13}{18}\right):x-1\frac{7}{33}:\frac{8}{11}=1\frac{2}{3}\)
các bạn ơi giúp tớ với
Các bạn làm giúp mk bài này với nha! (thanks)
TÍNH NHANH
\(\frac{1}{2}\)+\(\frac{1}{6}\)+\(\frac{1}{12}\)+\(\frac{1}{20}\)+\(\frac{1}{30}\)
(\(\frac{1}{9}\)-\(\frac{7}{19}\)) - \(\frac{3}{6}\) - (\(\frac{12}{19}\)-\(\frac{1}{2}\)) + \(\frac{5}{9}\)
\(\frac{2003}{1.2}\)+\(\frac{2003}{2.3}\)+\(\frac{2003}{3.4}\)+........ ...... .+\(\frac{2003}{2002.2003}\)
\(\frac{21}{36}\cdot\frac{5}{2}-\frac{7}{12}\cdot\frac{2}{7}+\left(2018-2019\right)^0\)
\(-12\frac{1}{3}-\frac{5}{7}+7\frac{1}{3}+1\frac{5}{7}+1^{2019}\)
GIUP MINH VOI!!!!!!
Bài 1: Thực hiện phép tính:
a, \(\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
b, \(\frac{-3}{7}.\frac{5}{9}+\frac{4}{9}.\frac{-3}{7}+2\frac{3}{7}\)
Bài 2: Tìm x
a, \(\frac{2}{3}.x-\frac{1}{2}.x=\frac{5}{12}\)
b, \(\left(2\frac{4}{5}x-50\right):\frac{2}{3}=51\)
a) \(\frac{1}{x-1}\)+\(\frac{-2}{3}\)(\(\frac{3}{4}\)-\(\frac{6}{5}\))=\(\frac{5}{2-2x}\)
b) 3-\(\frac{2}{2x-3}\)=\(\frac{2}{5}\)+\(\frac{2}{9-6x}\)-\(\frac{3}{2}\)
c) \(\frac{x}{2}\)-\(\frac{1}{x}\)=\(\frac{1}{12}\)
d) \(^{x^2}\)-\(\frac{7}{6}x\)+\(\frac{1}{3}\)=0
Mik đang cần gấp! Giúp mik với
Chứng minh rằng: \(\frac{1}{2^2}\)+\(\frac{1}{4^2}+\frac{1}{6^2}+...+\frac{1}{100^2}< \frac{1}{2}\)
1.Thực hiện phép tính:
a, A = \(2\frac{1}{3}+\frac{11}{5}:33-\frac{1}{50}.\left(-5\right)^2\)
b, B = \(\frac{4^9.9^4-10.6^9}{2^{10}.3^8+6^8.28}\)
2.Cho A = 1 +\(\frac{1}{2}+\frac{1}{3}+......+\frac{1}{4029}+\frac{1}{4030}\) và B = 1 + \(\frac{1}{3}+\frac{1}{5}+\frac{1}{7}+.....+\frac{1}{4027}+\frac{1}{4030}\)
So sánh \(\frac{A}{B}\) với \(1\frac{2015}{2016}\)
