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NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
27 tháng 8 2023
a, - \(\dfrac{2}{5}\) + \(\dfrac{4}{5}\).\(x\) = \(\dfrac{3}{5}\)
\(\dfrac{4}{5}\).\(x\) = \(\dfrac{3}{5}\)+ \(\dfrac{2}{5}\)
\(\dfrac{4}{5}\).\(x\) = 1
\(x\) = \(\dfrac{5}{4}\)
b, - \(\dfrac{3}{7}\) - \(\dfrac{4}{7}\): \(x\) = \(\dfrac{2}{5}\)
\(\dfrac{4}{7}\): \(x\) = - \(\dfrac{3}{7}\) - \(\dfrac{2}{5}\)
\(\dfrac{4}{7}\): \(x\) = - \(\dfrac{29}{35}\)
\(x\) = \(\dfrac{4}{7}\): (- \(\dfrac{29}{35}\) )
\(x\) = - \(\dfrac{20}{29}\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
27 tháng 8 2023
c, \(\dfrac{4}{7}\).\(x\) + \(\dfrac{2}{3}\) = - \(\dfrac{1}{5}\)
\(\dfrac{4}{7}\).\(x\) = -\(\dfrac{1}{5}\) - \(\dfrac{2}{3}\)
\(\dfrac{4}{7}\).\(x\) = - \(\dfrac{13}{15}\)
\(x\) = - \(\dfrac{13}{15}\): \(\dfrac{4}{7}\)
\(x\) = - \(\dfrac{91}{60}\)
20 tháng 12 2020
a) Ta có: \(\dfrac{1}{7}+x=-\dfrac{2}{3}\)
\(\Leftrightarrow x=-\dfrac{2}{3}-\dfrac{1}{7}=\dfrac{-14}{21}-\dfrac{3}{21}\)
hay \(x=-\dfrac{17}{21}\)
Vậy: \(x=-\dfrac{17}{21}\)
b) Ta có: \(\dfrac{-2}{3}:x=\dfrac{-5}{6}\)
\(\Leftrightarrow x=\dfrac{-2}{3}:\dfrac{-5}{6}=\dfrac{-2}{3}\cdot\dfrac{6}{-5}=\dfrac{-12}{-15}=\dfrac{4}{5}\)
Vậy: \(x=\dfrac{4}{5}\)
c) Ta có: \(\left(\dfrac{3}{5}-2x\right)\cdot\dfrac{5}{8}=1\)
\(\Leftrightarrow\left(\dfrac{3}{5}-2x\right)=1:\dfrac{5}{8}=\dfrac{8}{5}\)
\(\Leftrightarrow-2x=\dfrac{8}{5}-\dfrac{3}{5}=1\)
hay \(x=-\dfrac{1}{2}\)
Vậy: \(x=-\dfrac{1}{2}\)
d) Ta có: \(\dfrac{3}{4}+\dfrac{2}{5}x=\dfrac{29}{60}\)
\(\Leftrightarrow x\cdot\dfrac{2}{5}=\dfrac{29}{60}-\dfrac{3}{4}=\dfrac{29}{60}-\dfrac{45}{60}=\dfrac{-16}{60}=\dfrac{-4}{15}\)
hay \(x=\dfrac{-4}{15}:\dfrac{2}{5}=\dfrac{-4}{15}\cdot\dfrac{5}{2}=\dfrac{-20}{30}=-\dfrac{2}{3}\)
Vậy: \(x=-\dfrac{2}{3}\)
e) Ta có: \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)
\(\Leftrightarrow\dfrac{1}{4}:x=\dfrac{2}{5}-\dfrac{3}{4}=\dfrac{8}{20}-\dfrac{15}{20}=\dfrac{-7}{20}\)
hay \(x=-\dfrac{1}{4}:\dfrac{7}{20}=\dfrac{-1}{4}\cdot\dfrac{20}{7}=\dfrac{-20}{28}=\dfrac{-5}{7}\)
Vậy: \(x=-\dfrac{5}{7}\)
f) Ta có: \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)
\(\Leftrightarrow-x+\dfrac{11}{12}-\dfrac{2}{5}-\dfrac{2}{3}=0\)
\(\Leftrightarrow-x+\dfrac{55}{60}-\dfrac{24}{60}-\dfrac{40}{60}=0\)
\(\Leftrightarrow-x-\dfrac{9}{60}=0\)
\(\Leftrightarrow-x=\dfrac{9}{60}=\dfrac{3}{20}\)
hay \(x=-\dfrac{3}{20}\)
Vậy: \(x=-\dfrac{3}{20}\)
g) Ta có: \(\left|x+\dfrac{1}{3}\right|-4=\dfrac{-1}{2}\)
\(\Leftrightarrow\left|x+\dfrac{1}{3}\right|=\dfrac{-1}{2}+4=\dfrac{-1}{2}+\dfrac{8}{2}=\dfrac{7}{2}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=\dfrac{7}{2}\\x+\dfrac{1}{3}=-\dfrac{7}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{2}-\dfrac{1}{3}=\dfrac{21}{6}-\dfrac{2}{6}=\dfrac{19}{6}\\x=-\dfrac{7}{2}-\dfrac{1}{3}=\dfrac{-21}{6}-\dfrac{2}{6}=\dfrac{-23}{6}\end{matrix}\right.\)
Vậy: \(x\in\left\{\dfrac{19}{6};-\dfrac{23}{6}\right\}\)
28 tháng 8 2021
a) \(x:\dfrac{6}{13}=\dfrac{13}{7}\\ \Rightarrow x=\dfrac{13}{7}.\dfrac{6}{13}\\ \Rightarrow x=\dfrac{6}{7}\)
b) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}\\ \Rightarrow\dfrac{4}{7}.x=\dfrac{13}{15}\\ \Rightarrow x=\dfrac{91}{60}\)
c) \(\left(\dfrac{3}{10}-x\right):\dfrac{2}{5}=\dfrac{3}{5}\\ \Rightarrow\dfrac{3}{10}-x=\dfrac{6}{25}\\ \Rightarrow x=\dfrac{3}{50}\)
d) \(\dfrac{2}{3}x-\dfrac{7}{6}=\dfrac{5}{2}\\ \Rightarrow\dfrac{2}{3}x=\dfrac{11}{3}\\ \Rightarrow x=\dfrac{11}{2}\)
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)\(x=\left(\dfrac{7}{15}\cdot\dfrac{5}{3}\right)+\dfrac{3}{16}=\dfrac{7}{9}+\dfrac{3}{16}=\dfrac{139}{144}\)
4 tháng 5 2022
1.\(x\times\dfrac{2}{3}=\dfrac{1}{5}\)
\(x=\dfrac{1}{5}:\dfrac{2}{3}\)
\(x=\dfrac{3}{10}\)
2.\(\dfrac{2}{x}=\dfrac{12}{5}\)
\(12x=2.5\)
\(x=\dfrac{10}{12}=\dfrac{5}{6}\)
3.\(\dfrac{1}{2}x-\dfrac{3}{5}=-\dfrac{4}{5}\)
\(\dfrac{1}{2}x=\dfrac{-4}{5}+\dfrac{3}{5}\)
\(\dfrac{1}{2}x=-\dfrac{1}{5}\)
\(x=-\dfrac{1}{5}:\dfrac{1}{2}\)
\(x=-\dfrac{2}{5}\)
4.\(3x+2x=-5,05\)
\(5x=-5,05\)
\(x=-\dfrac{5,05}{5}\)
\(x=-1,01\)
O
4 tháng 5 2022
\(x\cdot\dfrac{2}{3}=\dfrac{1}{5}\)
\(x=\dfrac{1}{5}:\dfrac{2}{3}\)
\(x=\dfrac{1}{5}\cdot\dfrac{3}{2}\)
\(x=\dfrac{3}{10}\)
\(\dfrac{2}{x}=\dfrac{12}{5}\)
\(x=\dfrac{\left(2\cdot5\right)}{12}\)
\(x=\dfrac{10}{12}\)
\(x=\dfrac{5}{6}\)
\(\dfrac{1}{2}x-\dfrac{3}{5}=\dfrac{-4}{5}\)
\(\dfrac{1}{2}x=\left(\dfrac{-4}{5}+\dfrac{3}{5}\right)\)
\(\dfrac{1}{2}x=-\dfrac{1}{5}\)
\(x=\left(-\dfrac{1}{5}\right):\dfrac{1}{2}\)
\(x=\left(-\dfrac{1}{5}\right)\cdot2\)
\(x=-\dfrac{2}{5}\)
\(3x+2x=-5,05\)
\(\left(3+2\right)x=-5,05\)
\(5x=-5,05\)
\(x=\left(-5,05\right):5\)
\(x=-1,01\)
27 tháng 8 2023
a, 2/5 + 3/4 : x = -1/2
3/4 : x = -1/2 - 2/5
3/4 : x = -9/10
x = 3/4 : -9/10
x = -5/6
27 tháng 8 2023
b, 5/7 - 2/3 . x = 4/5
2/3 . x = 4/5 + 5/7
2/3 . x = 53/35
x = 53/35 : 2/3
x = 159/70
17 tháng 7 2023
a) \(\dfrac{8}{9}x=\dfrac{2}{7}-\dfrac{2}{3}=-\dfrac{8}{21}\)
\(x=-\dfrac{8}{21}:\dfrac{8}{9}=-\dfrac{3}{7}\)
b) \(\dfrac{2}{5}x=\dfrac{2}{5}-\dfrac{2}{5}=0\)
\(x=0:\dfrac{2}{5}=0\)
c)\(\dfrac{7}{8}x=\dfrac{2}{9}-\dfrac{1}{3}=-\dfrac{1}{9}\)
\(x=-\dfrac{1}{9}:\dfrac{7}{8}=-\dfrac{8}{63}\)
NM
17 tháng 7 2023
a) 2/7 - 8/9 . x = 2/3
⇒ 8/9 . x = 2/7 - 2/3
⇒ 8/9 .x = -8/21
⇒ x = -8/21 : 8/9
⇒ x = -3/7.
Vậy...
28 tháng 6 2023
2:
a: =>2/3:x=1,4-2,4=-1
=>x=-2/3
b: =>x/5=25/30-19/30=6/30=1/5
=>x=1
3:
Số học sinh giỏi là 40*1/4=10 bạn
Số học sinh khá là 30*3/5=18 bạn
Số học sinh TB là 30-18=12 bạn
25 tháng 3 2022
\(\dfrac{1}{5}+\dfrac{2}{11}< \dfrac{x}{55}< \dfrac{2}{5}+\dfrac{1}{5}\)
\(\dfrac{11+10}{55}< \dfrac{x}{55}< \dfrac{3}{5}\)
\(\dfrac{21}{55}< \dfrac{x}{55}< \dfrac{33}{55}\)
Vậy \(x\in\left\{22;23;24;...\right\}\)
14 tháng 8 2023
a: x+2/5=1/2
=>x=1/2-2/5=5/10-4/10=1/10
b; x-2/5=2/7
=>x=2/7+2/5=10/35+14/35=24/35
c: 3/5-x=1/10
=>x=3/5-1/10=6/10-1/10=5/10=1/2
d: x*3/4=9/20
=>x=9/20:3/4=9/20*4/3=36/60=3/5
e: x:1/7=14
=>x=14*1/7=2
f: =>x+1/4=2/5:1/2=4/5
=>x=4/5-1/4=16/20-5/20=11/20
g: =>x*2/3=9/12+2/3=3/4+2/3=9/12+8/12=17/12
=>x=17/12:2/3=17/12*3/2=51/24=17/8
\(\dfrac{-5}{2}x+\dfrac{3}{5}=\dfrac{2}{5}\)
\(\dfrac{-5}{2}x=\dfrac{2}{5}-\dfrac{3}{5}\)
\(\dfrac{-5}{2}x=-\dfrac{1}{5}\)
\(x=-\dfrac{1}{5}:\dfrac{-5}{2}\)
\(x=\dfrac{2}{25}\)
\(\dfrac{-5}{2}x+\dfrac{3}{5}=\dfrac{2}{5}\)
\(\Rightarrow\dfrac{-5}{2}x=\dfrac{2}{5}-\dfrac{3}{5}\)
\(\Rightarrow\dfrac{-5}{2}x=\dfrac{-1}{5}\)
\(\Rightarrow x=\dfrac{-1}{5}:\dfrac{-5}{2}\)
\(\Rightarrow x=\dfrac{-1}{5}\cdot\dfrac{2}{-5}\)
\(\Rightarrow x=\dfrac{2}{25}\)