\(-2+\dfrac{-5}{8}=-\dfrac{16}{8}+-\dfrac{5}{8}=-\dfrac{21}{8}\)
Cho A = 40 + \(\dfrac{3}{8}+\dfrac{7}{8^2}+\dfrac{5}{8^3}+\dfrac{32}{8^5}\)
B = \(\dfrac{24}{8^2}+40+\dfrac{5}{8^2}+\dfrac{40}{8^4}+\dfrac{5}{8^4}\)
So sánh A và B
Tính:
a) \(\dfrac{-7}{8}\) . \(\dfrac{3}{5}\) - \(\dfrac{2}{5}\) . \(\dfrac{7}{8}\) + \(3\dfrac{7}{8}\)
b) -1,6 : ( 1 + \(\dfrac{2}{3}\) )
c) \(\dfrac{6}{7}\) + \(\dfrac{5}{8}\) : 5 - \(\dfrac{3}{16}\) . ( -2 )\(^2\)
d) \(\dfrac{1^2}{1.2}\) . \(\dfrac{2^2}{2.3}\) . \(\dfrac{3^2}{3.4}\) . \(\dfrac{4^2}{4.5}\)
Tính:
a, \(\dfrac{3}{5}+\dfrac{-4}{9}\) b, \(\dfrac{3}{5}+\dfrac{2}{5}.\dfrac{15}{8}\)
c, \(\dfrac{7}{2}.\dfrac{8}{13}+\dfrac{8}{13}.\dfrac{-5}{2}+\dfrac{8}{13}\)
d, \(\dfrac{-5}{17}.\dfrac{-9}{23}+\dfrac{9}{23}.\dfrac{-22}{17}+11\dfrac{9}{23}\)
thực hiện phép tính
\(\dfrac{\dfrac{2}{3}-}{\dfrac{8}{3}-}\dfrac{\dfrac{2}{5}+}{\dfrac{8}{5}+}\dfrac{\dfrac{2}{7}}{\dfrac{8}{7}}\)
8. \(\dfrac{-5}{9}\) + \(\dfrac{8}{15}\) + \(\dfrac{-2}{11}\) + \(\dfrac{4}{-9}\) + \(\dfrac{7}{15}\)
9. \(\dfrac{2}{7}\) + (\(\dfrac{-2}{5}\) + \(\dfrac{5}{7}\))
10. \(\dfrac{7}{19}\). \(\dfrac{8}{11}\) + \(\dfrac{3}{11}\).\(\dfrac{7}{19}\)+\(\dfrac{-12}{19}\)
11. \(\dfrac{-5}{7}\).\(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\).\(\dfrac{9}{11}\)
12. \(\dfrac{-5}{13}\) + \(\dfrac{5}{7}\) + \(\dfrac{20}{41}\) + \(\dfrac{-8}{13}\) + \(\dfrac{21}{41}\)
Giúp tớ với ạ! Tớ cảm ơn! Các cậu chỉ cần ghi đáp án cuối cùng thôi ạ! Cảm ơn các cậu<3
a) \(\dfrac{2}{7}-\dfrac{8}{9}.x=\dfrac{2}{3}\)
b) \(\dfrac{2}{5}-\dfrac{2}{5}x=\dfrac{2}{5}\)
c) \(\dfrac{2}{9}-\dfrac{7}{8}x=\dfrac{1}{3}\)
\(\dfrac{-2}{5}.\dfrac{5}{8}+\dfrac{5}{8}.\dfrac{3}{5}\)
Bài 4. Tìm x biết:
a. \(\dfrac{x}{5}=\dfrac{2}{5},\dfrac{3}{8}=\dfrac{6}{x},\dfrac{1}{9}=\dfrac{x}{27}\)
b. \(\dfrac{4}{x}=\dfrac{8}{6},\dfrac{3}{x-5}=\dfrac{-4}{x+2},\dfrac{x}{-2}=\dfrac{-8}{x}\)
\(\dfrac{-1}{8}+\dfrac{-5}{8}\)
\(\dfrac{-3}{7}+\dfrac{5}{7}\)
\(\dfrac{3}{5}+\dfrac{-7}{4}\)
\(\dfrac{-2}{3}+\dfrac{1}{5}\)
\(\dfrac{-2}{13}+\dfrac{-5}{26}\)
\(\dfrac{-4}{7}+\dfrac{1}{3}\)
a)\(\dfrac{8}{5}\cdot\dfrac{2}{3}+\dfrac{-5\cdot5}{3\cdot5}\)
b) \(\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}\left(-2\right)^2\)
