\(2-\dfrac{9}{-21}=\dfrac{21}{21}+\dfrac{9}{21}=\dfrac{30}{21}\)
`2 - 9/(-21) = 2 - 3/(-7) = 2 + 3/7 = 14/7 + 3/7 = (14+3)/7 = 17/7`
\(2-\dfrac{9}{-21}=2-\dfrac{-9}{21}=2+\dfrac{9}{21}=2+\dfrac{3}{7}=\dfrac{14}{7}+\dfrac{3}{7}=\dfrac{17}{7}\)
\(2-\dfrac{9}{-21}=\dfrac{21}{21}+\dfrac{9}{21}=\dfrac{30}{21}\)
`2 - 9/(-21) = 2 - 3/(-7) = 2 + 3/7 = 14/7 + 3/7 = (14+3)/7 = 17/7`
\(2-\dfrac{9}{-21}=2-\dfrac{-9}{21}=2+\dfrac{9}{21}=2+\dfrac{3}{7}=\dfrac{14}{7}+\dfrac{3}{7}=\dfrac{17}{7}\)
\(a,\dfrac{3}{5}+\dfrac{-5}{9}\)
\(b,\dfrac{1}{3}+\dfrac{-4}{3};\dfrac{4}{7}\)
\(c,-\dfrac{27}{23}+\dfrac{5}{21}+\dfrac{4}{23}+\dfrac{16}{21}+\dfrac{1}{2}\)
\(d,\dfrac{-8}{9}+\dfrac{1}{9}.\dfrac{2}{9}+\dfrac{1}{9}.\dfrac{7}{9}\)
\(\dfrac{2}{3}.\dfrac{-5}{7}\)
\(\dfrac{-1}{3}.\dfrac{5}{9}\)
\(\dfrac{-2}{5}.\dfrac{10}{4}\)
\(\dfrac{-3}{7}.\dfrac{5}{15}\)
\(\dfrac{-7}{3}.\dfrac{9}{21}\)
\(\dfrac{7}{21}+\dfrac{-9}{36}\)
\(\dfrac{-12}{18}+\dfrac{-21}{35}\)
\(\dfrac{-18}{24}+\dfrac{15}{-21}\)
\(\dfrac{3}{21}+\dfrac{-6}{42}\)
\(\dfrac{9}{17}\) x \(\dfrac{21}{13}\) + \(\dfrac{9}{17}\) x \(\dfrac{5}{13}\) - \(\dfrac{9}{17}\) x 2
Các bạn giải giúp mình chi tiết nha! Tks
\(\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{2}{9}\)
Tìm x, biết:
a) \(\left(3\dfrac{1}{2}-2.x\right).3\dfrac{1}{3}=7\dfrac{1}{3}\)
b) \(\dfrac{4}{9}.x=\dfrac{9}{8}-0,125\)
c) \(\dfrac{-X}{21}=\dfrac{20}{7}\)
\(-\dfrac{10}{21}.\left[\dfrac{9}{15}+\left(\dfrac{3}{5}\right)^2\right]\)
tìm x thuộc N biết:
\(\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+....+\dfrac{2}{x\left(x+1\right)}=\dfrac{2}{9}\)
\(\dfrac{5}{7}-x=\dfrac{9}{21}\)
\(-x-\dfrac{1}{3}=\dfrac{2}{6}\)
\(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)