Tính nhanh nếu có thể
1. \(\dfrac{-1}{24}-[\dfrac{1}{4}-\left(\dfrac{1}{2}-\dfrac{7}{8}\right)]\)
2. \((\dfrac{5}{7}-\dfrac{7}{5})-[\dfrac{1}{2}-(-\dfrac{2}{7}-\dfrac{1}{10})]\)
3.\(\dfrac{1}{3\cdot5}+\dfrac{1}{5\cdot7}+\dfrac{1}{7\cdot9}+.......+\dfrac{1}{2015\cdot2017}\)
(\(\dfrac{1}{4\cdot9}+\dfrac{1}{9\cdot14}+\dfrac{1}{14\cdot19}+...+\dfrac{1}{44\cdot49}\)) .Tính tổng
1)Thực hiện phép tính
a) \(\dfrac{9^8\cdot5^6}{3^7\cdot27^3\cdot25^4}\) b) \(\dfrac{5^{20}\cdot6^{18}}{15^{20}\cdot4^{10}}\) c) \(\left(\dfrac{1}{3}\right)^{50}\cdot9^{25}-\left(\dfrac{2}{3}\right)^{100}:\left(\dfrac{8}{27}\right)^{33}\) d) \(\left(\dfrac{3}{8}\right)^{60}\cdot\left(\dfrac{2}{3}\right)^{60}:\left(\dfrac{1}{2}\right)^{119}\cdot\left(\dfrac{1}{2}\right)\)
2) Tìm x, biết:
a) \(\dfrac{x}{12}=\dfrac{5}{x}\) b)\(8^x=2^{2x+3}\) c)\(\dfrac{1}{2}\sqrt{\dfrac{1}{2}x-2}-\dfrac{2}{3}=\dfrac{1}{3}\)
\(\dfrac{-4}{5}\cdot13\dfrac{1}{3}-\dfrac{4}{5}\cdot\left(-13\dfrac{1}{2}\right)\)Tính
tính\(\dfrac{4.5:\left[47\cdot375-\left(26\dfrac{1}{3}-18\cdot0.75\right)\cdot2.4:0.88\right]}{17.81:1037-23\dfrac{2}{3}:1\dfrac{5}{6}}\)
Tính:
\(A=1-\dfrac{10}{18}-\dfrac{10}{63}-\dfrac{10}{133}-\dfrac{10}{228}-...-\dfrac{10}{4653}-\dfrac{10}{5148}\)
Tính nhanh : \(\dfrac{7}{8}\div\left(\dfrac{2}{9}-\dfrac{1}{18}\right)+\dfrac{7}{8}\div\left(\dfrac{1}{36}-\dfrac{5}{12}\right)\)
câu 1 . tìm x
a. \(x:3\dfrac{1}{15}=1\dfrac{1}{2}\)
b.\(x.\dfrac{3}{2}=\dfrac{-7}{6}\)
c. \(\dfrac{5}{6}+\dfrac{1}{4}:x=\dfrac{-2}{3}\)
d. \(\dfrac{-2}{13}.x=\dfrac{-9}{26}\)
e. \(\dfrac{1}{2}.x-\dfrac{1}{10}=\dfrac{2}{3}\)
f.\(-52+\dfrac{2}{3}.x=-46\)
CMR : \(\dfrac{1}{1.2}+\dfrac{1}{3.4}+...+\dfrac{1}{49.50}=\dfrac{1}{26}+\dfrac{1}{27}+...+\dfrac{1}{50}\)
