Tính.
a.\(\dfrac{3}{5}\) x \(\dfrac{6}{7}\) b. \(\dfrac{2}{9}\) x \(\dfrac{18}{3}\) c. \(\dfrac{5}{7}\) x 12 d. \(\)21 x \(\dfrac{2}{7}\)
K
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Những câu hỏi liên quan
GL
24 tháng 8 2023
a) \(\dfrac{2}{3}-\dfrac{2}{6}=\dfrac{4}{6}-\dfrac{2}{6}=\dfrac{4-2}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)
b) \(\dfrac{5}{6}-\dfrac{3}{18}=\dfrac{10}{18}-\dfrac{3}{18}=\dfrac{10-3}{18}=\dfrac{7}{18}\)
c) \(\dfrac{8}{14}-\dfrac{2}{7}=\dfrac{8}{14}-\dfrac{4}{14}=\dfrac{8-4}{14}=\dfrac{4}{14}=\dfrac{2}{7}\)
d) \(\dfrac{12}{20}-\dfrac{2}{5}=\dfrac{12}{20}-\dfrac{8}{20}=\dfrac{12-8}{20}=\dfrac{4}{20}=\dfrac{1}{5}\)
19 tháng 2 2022
\(\dfrac{5}{7}-x=\dfrac{9}{21}\\ \Rightarrow\dfrac{5}{7}-x=\dfrac{3}{7}\\ \Rightarrow x=\dfrac{5}{7}-\dfrac{3}{7}\\ \Rightarrow x=\dfrac{2}{7}\\ b,-x-\dfrac{1}{3}=\dfrac{2}{6}\\ \Rightarrow-x=\dfrac{2}{6}+\dfrac{1}{3}\\ \Rightarrow-x=\dfrac{2}{3}\\ \Rightarrow x=-\dfrac{2}{3}\\ \dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\\ \Rightarrow\dfrac{-5}{6}-x=\dfrac{1}{4}\\ \Rightarrow x=\dfrac{-5}{6}-\dfrac{1}{4}\\ \Rightarrow x=-\dfrac{13}{12}\)
GL
24 tháng 8 2023
a) \(\dfrac{2}{3}+\dfrac{4}{9}=\dfrac{6}{9}+\dfrac{4}{9}+\dfrac{6+3}{9}=\dfrac{10}{9}\)
b)\(\dfrac{1}{10}+\dfrac{2}{5}=\dfrac{1}{10}+\dfrac{4}{10}=\dfrac{1+4}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)
c) \(\dfrac{7}{22}-\dfrac{3}{11}=\dfrac{7}{22}-\dfrac{6}{22}=\dfrac{7-6}{22}=\dfrac{1}{22}\)
d) \(\dfrac{5}{6}-\dfrac{5}{12}=\dfrac{10}{12}-\dfrac{5}{12}=\dfrac{10-5}{12}=\dfrac{5}{12}\)
HQ
Hà Quang Minh
Giáo viên
27 tháng 11 2023
a) $\frac{3}{5} \times \frac{6}{7} = \frac{{3 \times 6}}{{5 \times 7}} = \frac{{18}}{{35}}$
b) $\frac{2}{9} \times \frac{{18}}{3} = \frac{{2 \times 18}}{{9 \times 3}} = \frac{{36}}{{27}} = \frac{4}{3}$
c) $\frac{5}{7} \times 12 = \frac{{5 \times 12}}{7} = \frac{{60}}{7}$
d) $21 \times \frac{2}{7} = \frac{{21 \times 2}}{7} = \frac{{42}}{7} = 6$
O
15 tháng 5 2022
a) \(\dfrac{3}{5}+\dfrac{1}{6}=\dfrac{18}{30}+\dfrac{5}{30}=\dfrac{23}{30}\)
b) \(4+\dfrac{2}{5}=\dfrac{20}{5}+\dfrac{2}{5}=\dfrac{22}{5}\)
c) \(\dfrac{25}{12}-\dfrac{7}{6}=\dfrac{25}{12}-\dfrac{14}{12}=\dfrac{11}{12}\)
d) \(\dfrac{9}{7}-\dfrac{7}{6}=\dfrac{54}{42}-\dfrac{49}{42}=\dfrac{5}{42}\)
d) \(\dfrac{3}{7}\times\dfrac{2}{5}=\dfrac{3\times2}{7\times5}=\dfrac{6}{35}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
17 tháng 8 2023
b, \(x+\dfrac{2}{3}\) = \(\dfrac{3}{5}\) - \(\dfrac{-1}{6}\)
\(x+\dfrac{2}{3}\) = \(\dfrac{23}{30}\)
\(x\) = \(\dfrac{23}{30}\) - \(\dfrac{2}{3}\)
\(x\) = \(\dfrac{1}{10}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
17 tháng 8 2023
a, \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)
\(\dfrac{2}{5}+x\) = \(\dfrac{11}{12}-\dfrac{2}{3}\)
\(\dfrac{2}{5}-x\) = \(\dfrac{1}{4}\)
x = \(\dfrac{2}{3}-\dfrac{1}{4}\)
\(x=\dfrac{5}{12}\)
GL
24 tháng 8 2023
a) \(\dfrac{1}{2}-\dfrac{1}{6}=\dfrac{3}{6}-\dfrac{1}{6}=\dfrac{3-1}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)
b) \(\dfrac{3}{4}-\dfrac{5}{8}=\dfrac{12}{8}-\dfrac{5}{8}=\dfrac{12-5}{8}=\dfrac{7}{8}\)
c) \(\dfrac{7}{10}-\dfrac{2}{5}=\dfrac{7}{10}-\dfrac{4}{10}=\dfrac{7-4}{10}=\dfrac{3}{10}\)
d) \(\dfrac{7}{12}-\dfrac{1}{3}=\dfrac{7}{12}-\dfrac{4}{12}=\dfrac{7-4}{12}=\dfrac{3}{12}=\dfrac{1}{4}\)
NV
Nguyễn Việt Dũng
CTVVIP
24 tháng 8 2023
a) \(\dfrac{1}{3}\)
b)\(\dfrac{1}{8}\)
c)\(\dfrac{3}{10}\)
d)\(\dfrac{3}{12}\)
TC
7 tháng 4 2022
a)\(x=\left(\dfrac{3}{56}\cdot\dfrac{28}{9}\right):\dfrac{-3}{7}=\dfrac{1}{6}:\dfrac{-3}{7}=-\dfrac{7}{18}\)
b)\(x=\left(\dfrac{7}{15}\cdot\dfrac{5}{3}\right)+\dfrac{3}{16}=\dfrac{7}{9}+\dfrac{3}{16}=\dfrac{139}{144}\)
28 tháng 12 2021
\(a,\dfrac{x}{5}=\dfrac{-18}{10}\\ \Rightarrow x=-\dfrac{18}{10}.5\\ \Rightarrow x=-9\\ b,\dfrac{6}{x-1}=\dfrac{-3}{7}\\ \Rightarrow6.7=-3\left(x-1\right)\\ \Rightarrow42=-3x+3\\ \Rightarrow42+3x-3=0\\ \Rightarrow3x+39=0\\ \Rightarrow3x=-39\\ \Rightarrow x=-13\\ c,\dfrac{y-3}{12}=\dfrac{3}{y-3}\\ \Rightarrow\left(y-3\right)^2=36\\ \Rightarrow\left[{}\begin{matrix}y-2=6\\y-2=-6\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}y=8\\y=-4\end{matrix}\right.\)
\(d,\dfrac{x}{25}=\dfrac{-5}{x^2}\\ \Rightarrow x^3=-125\\ \Rightarrow x^3=\left(-5\right)^3\\ \Rightarrow x=-5\)
a) \(\dfrac{3}{5}\times\dfrac{6}{7}=\dfrac{18}{35}\)
b) \(\dfrac{2}{9}\times\dfrac{18}{3}=\dfrac{4}{3}\)
c) \(\dfrac{5}{7}\times12=\dfrac{60}{7}\)
d) \(21\times\dfrac{2}{7}=6\)