1 + \(\dfrac{19}{120}\)<\(\dfrac{x}{36}\)<\(\dfrac{58}{90}\)+\(\dfrac{59}{72}\)
bài 45: Tìm x, biết:
a) x=\(\dfrac{-1}{2}+\dfrac{3}{4}\); b) \(\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}\)
Tính nhanh
A=1+\(\dfrac{1}{8}+\dfrac{1}{24}+\dfrac{1}{48}+\dfrac{1}{80}+\dfrac{1}{120}\)
Tính A =\(\dfrac{1}{6}+\dfrac{1}{10}+\dfrac{1}{15}+\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+\dfrac{1}{45}+\dfrac{1}{55}+\dfrac{1}{66}+\dfrac{1}{78}\)
Với m,n∈Zm,n∈Z ; sao cho \(\dfrac{1}{m}\)+\(\dfrac{n}{6}\)=12. Số cặp giá trị (m;n)(m;n) thỏa mãn là
\(\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+....+\dfrac{1}{99}+\dfrac{1}{x.\left(x+1\right)}=\dfrac{1}{2001}\)
Tìm \(x\) biết :
a) \(x=\dfrac{-1}{2}+\dfrac{3}{4}\)
b) \(\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}\)
\(Tìmxbiết\dfrac{1}{5.8}+\dfrac{1}{8.11}+\dfrac{1}{11.14}+...+\dfrac{1}{x+\left(x+3\right)}\)
\(\dfrac{19}{1}+\dfrac{18}{2}+...+\dfrac{1}{19}\)