\(\frac{10}{3.8}+\frac{10}{8.13}+\frac{10}{13.18}+...+\frac{10}{48.53}\)
\(=\frac{10}{5}\left(\frac{1}{3}-\frac{1}{8}+\frac{1}{8}-\frac{1}{13}+\frac{1}{13}-\frac{1}{18}+...+\frac{1}{48}-\frac{1}{53}\right)\)
\(=2\left(\frac{1}{3}-\frac{1}{53}\right)\)
\(=2.\frac{50}{159}=\frac{100}{159}\)
Tinh A=\(\frac{10}{3.8}\)+\(\frac{10}{8.13}\)+\(\frac{10}{13.18}\)+\(\frac{10}{18.23}\)+\(\frac{10}{23.28}\)
\(B=\)\(\frac{10}{3.8}\)\(+\frac{10}{8.13}\)\(+\frac{10}{13.18}\)\(+\frac{10}{18.23}\)\(+\frac{10}{23.28}\)
Bài 5: (1 điểm ) Tính
\(\left(\frac{5^3}{8.13}+\frac{5^3}{13.18}+\frac{5^3}{18.23}+...+\frac{5^3}{93.98}\right).3\frac{17}{125}\)
Tính nhanh:
a) \(A=\frac{3}{5.8}\)+ \(\frac{3}{8.11}\)+ \(\frac{3}{11.14}\)+ ... + \(\frac{3}{2006.2009}\)
b) \(B=\frac{1}{6.10}\)+ \(\frac{1}{10.14}\)+ \(\frac{1}{14.18}\)+...+ \(\frac{1}{402.406}\)
c) \(C=\frac{10}{7.12}\)+\(\frac{10}{12.17}\)+\(\frac{10}{17.22}\)+...+\(\frac{10}{502.507}\)
d) \(D=\frac{4}{8.13}\)+\(\frac{4}{13.18}\)+\(\frac{4}{18.23}\)+...+\(\frac{4}{253.258}\)
Tính:A=1/7.12+1/12.17+1/17.22+...+1/52.57
B=10/8.13+10/13.18+10/18.23+...+10/253.258
Tìm x:( 1 phần 3.8+ 1 phần 8.13+ 1 phần 13.18+…+1 phần 33.38)-x= 31 phần 114
mọi người ơi giúp mik với....thanks ....
TINH\(C=\frac{x}{2008}-\frac{1}{10}-\frac{1}{15}-\frac{1}{21}-...-\frac{1}{120}=\frac{5}{8}\)
a) Tính A=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+..........+\frac{10}{1400}\)
b) Tìm x thuộc Z , biết \(\frac{1.2+2.3+3.4+....+99.100}{x^2+\left(x^2+1\right)+\left(x^2+2\right)+.....+\left(x^2+99\right)}=50\frac{116}{131}\)
a.So sánh (không quy đồng): \(A=\frac{-7}{10^{2005}}+\frac{-15}{10^{2006}};B=\frac{-15}{10^{2005}}+\frac{_{-7}}{10^{2006}}\)
b.Tìm x: \(\frac{1}{5.8}+\frac{1}{8.11}+\frac{1}{11.14}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\)
Làm đc mình tick cho!!!!!!
