KC
2
K
Khách
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TD
2
28 tháng 3 2017
\(\dfrac{5}{7}x-x=1\dfrac{1}{7}\\ < =>\dfrac{5}{7}x-x=\dfrac{8}{7}\\ < =>\left(\dfrac{5}{7}-\dfrac{7}{7}\right)x=\dfrac{8}{7}\\ < =>-\dfrac{2}{7}x=\dfrac{8}{7}\\ =>x=\dfrac{\dfrac{8}{7}}{-\dfrac{2}{7}}=-4\)
2 tháng 5 2017
\(\dfrac{1}{7}.2\dfrac{1}{3}+\dfrac{5}{2}.\dfrac{3}{7}-\dfrac{59}{6}.\dfrac{1}{7}\)
=\(\dfrac{1}{7}.\dfrac{7}{3}+\dfrac{5}{2}.\dfrac{3}{7}-\dfrac{59}{6}.\dfrac{1}{7}\)
=\(\dfrac{1}{7}.\left(\dfrac{7}{3}-\dfrac{59}{6}\right)+\dfrac{5}{2}.\dfrac{3}{7}\)
=\(\dfrac{1}{7}.\dfrac{-15}{2}+\dfrac{5}{2}.\dfrac{3}{7}\)
=\(\dfrac{-15}{14}+\dfrac{15}{14}\)
= 0
NV
3
19 tháng 2 2022
\(=\left(\dfrac{88}{132}-\dfrac{33}{132}+\dfrac{60}{132}\right):\left(\dfrac{55}{132}-\dfrac{132}{132}-\dfrac{84}{132}\right)\)
\(=\dfrac{115}{-161}=-\dfrac{115}{161}\)
ND
1
2 tháng 5 2017
=\(\dfrac{6}{7}+\dfrac{5}{8}.\dfrac{1}{5}-\dfrac{3}{16}.\left(-4\right)\)
= \(\dfrac{6}{7}+\dfrac{5.1}{8.5}-\dfrac{3.\left(-4\right)}{16}\)= \(\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{-3}{4}\)= \(\dfrac{48}{56}+\dfrac{7}{56}-\dfrac{-42}{56}\)
= \(\dfrac{48+7-\left(-42\right)}{56}\)=\(\dfrac{97}{56}\)
HQ
Hà Quang Minh
Giáo viên
18 tháng 8 2023
\(\dfrac{1}{4}\cdot\dfrac{1}{3}+\dfrac{1}{6}\cdot\dfrac{1}{4}+\dfrac{1}{4}\cdot\dfrac{1}{7}\\ =\dfrac{1}{4}\cdot\left(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{7}\right)\\ =\dfrac{1}{4}\cdot\dfrac{9}{14}\\ =\dfrac{9}{56}\)
TT
18 tháng 4 2018
\(\dfrac{\dfrac{3}{7}-\dfrac{3}{11}+\dfrac{3}{13}}{\dfrac{5}{7}-\dfrac{5}{11}+\dfrac{5}{13}}+\dfrac{\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{4}}{\dfrac{5}{4}-\dfrac{5}{6}+\dfrac{5}{8}}\)
\(=\dfrac{3\left(\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{13}\right)}{5\left(\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{13}\right)}+\dfrac{2(\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{8})}{5\left(\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{8}\right)}\)
\(=\dfrac{3}{5}+\dfrac{2}{5}\)
\(=1\)
LK
25 tháng 4 2018
a,
= \(\dfrac{20}{100}.\dfrac{15}{36}-\)(\(\dfrac{2}{5}+\dfrac{2}{3}\)):\(\dfrac{6}{5}\)
= \(\dfrac{20.15}{100.36}\)- ( \(\dfrac{6}{15}+\dfrac{10}{15}\)): \(\dfrac{6}{5}\)
= \(\dfrac{1.5}{5.12}-\dfrac{16}{15}:\dfrac{6}{5}\)
= \(\dfrac{1.1}{1.12}-\dfrac{16.5}{10.6}\)
= \(\dfrac{1}{12}-\dfrac{16.1}{2.6}\)
= \(\dfrac{1}{12}\) - \(\dfrac{16}{12}\)
= \(\dfrac{1}{12}+\dfrac{\left(-16\right)}{12}\)
= \(\dfrac{15}{12}\) = \(\dfrac{5}{4}\)
b,
= \(\dfrac{6}{7}+\dfrac{5}{4}+\dfrac{\left(-4\right)}{7}+\dfrac{25}{4}\)
= (\(\dfrac{6}{7}+\dfrac{\left(-4\right)}{7}\)) + (\(\dfrac{5}{4}+\dfrac{25}{4}\))
= \(\dfrac{2}{7}+\dfrac{30}{4}\)
= \(\dfrac{2}{7}+\dfrac{15}{2}\)
= \(\dfrac{4}{14}+\dfrac{105}{14}\)
= \(\dfrac{109}{14}\)
1/3 . 6/(-7) = -6/21 = -2/7
\(\dfrac{1}{3}\). \(\dfrac{6}{-7}\) = \(\dfrac{ }{7}\)
\(\dfrac{2}{-7}\) = \(\dfrac{ }{7}\)
\(◻\) = \(\dfrac{2}{-7}\) x 7
\(◻\) = \(-2\)