Tìm \(x\), biết :
a) \(0,5x-\dfrac{2}{3}x=\dfrac{7}{12}\) b) \(x:4\dfrac{1}{3}=-2,5\)
c) \(5,5x=\dfrac{13}{15}\) d) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
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Tìm x, biết:
a) 0,5x - \(\dfrac{2}{3}\)x = \(\dfrac{7}{12}\)
b) x : 4\(\dfrac{1}{3}\) = -2,5
c) 5,5x = \(\dfrac{13}{15}\)
d) (\(\dfrac{3x}{7}\)+ 1) : (-4) = \(\dfrac{-1}{28}\)
a) \(0,5x-\dfrac{2}{3}x=\dfrac{7}{12}\)
\(\dfrac{1}{2}x-\dfrac{2}{3}x=\dfrac{7}{12}\)
\(\left(\dfrac{1}{2}-\dfrac{2}{3}\right)x=\dfrac{7}{12}\)
\(\dfrac{-1}{6}x=\dfrac{7}{12}\)
\(x=\dfrac{7}{12}:\dfrac{-1}{6}\)
\(x=\dfrac{-7}{2}\)
b) \(x:4\dfrac{1}{3}=-2,5\)
\(x:\dfrac{13}{3}=\dfrac{-5}{2}\)
\(x=\dfrac{13}{3}.\dfrac{-5}{2}\)
\(x=\dfrac{-65}{6}\)
c) \(5,5x=\dfrac{13}{15}\)
\(\dfrac{11}{2}x=\dfrac{13}{15}\)
\(x=\dfrac{13}{15}:\dfrac{11}{2}\)
\(x=\dfrac{26}{165}\)
d) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
\(\left(\dfrac{3x}{7}+1\right)=\dfrac{-1}{28}.\left(-4\right)\)
\(\dfrac{3x}{7}+1=\dfrac{1}{7}\)
\(\dfrac{3x}{7}=\dfrac{1}{7}-1\)
\(\dfrac{3x}{7}=\dfrac{-6}{7}\)
\(\Rightarrow3x=-6\\ x=\left(-6\right):3\\ x=-2\)
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câu d mình nhầm bạn nha
d)\(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
\(\dfrac{3x}{7}+1=\dfrac{-1}{28}.\left(-4\right)\)
\(\left(\dfrac{3x}{7}+1\right)=\dfrac{1}{7}\)
\(\dfrac{3x}{7}=\dfrac{1}{7}-1\)
\(\dfrac{3x}{7}=\dfrac{-6}{7}\)
Ta có : 3x =-6
x = -6:3
x=-2
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a) 0,5x-\(\dfrac{2}{3}x=\dfrac{7}{12}\)
x\(\left(\dfrac{1}{2}-\dfrac{2}{3}\right)=\dfrac{7}{12}\)
\(\dfrac{-1}{6}x=\dfrac{7}{12}\)
x = \(\dfrac{7}{12}:\dfrac{-1}{6}\)
x =\(\dfrac{-7}{2}\)
b)\(x:4\dfrac{1}{3}=-2,5\)
\(x:\dfrac{13}{3}=\dfrac{-25}{10}\)
\(x=\dfrac{-5}{2}:\dfrac{13}{3}\)
\(x=\dfrac{-15}{26}\)
c)5,5\(x\)=\(\dfrac{13}{15}\)
\(\dfrac{11}{2}\)\(x\)=\(\dfrac{13}{15}\)
\(x=\dfrac{13}{15}:\dfrac{11}{2}\)
\(x=\dfrac{26}{165}\)
d)\(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
\(\dfrac{3x}{7}+1\)=\(\dfrac{-1}{28}:\left(-4\right)\)
\(\left(\dfrac{3x}{7}+1\right)=\dfrac{1}{112}\)
\(\dfrac{3x}{7}=\dfrac{1}{112}-1\)
\(\dfrac{3x}{7}=\dfrac{-111}{112}\)
ta có 3x.112=-111.7
3x.112=-777
Vì -777 \(⋮̸̸\)112
\(\Rightarrow\) Bài sai
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Tìm \(x\) :
\(a.1\dfrac{2}{4}x-1\dfrac{2}{3}=2\dfrac{3}{5}\) \(b.0,5x-\dfrac{2}{3}x=\dfrac{7}{12}\) \(c.5,5x=\dfrac{1}{2}\)
a: =>3/2x=64/15
=>x=128/45
b: =>-1/6x=7/12
=>x=-7/2
c: =>11/2*x=1/2
=>x=1/2:11/2=1/11
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tìm x , biết:a) x : 4dfrac{1}{3} -2,5 b) dfrac{3}{5}x + dfrac{1}{4} dfrac{1}{10}c) 2dfrac{7}{9} - dfrac{12}{13}x dfrac{7}{9} d)dfrac{-2}{3}-dfrac{1}{3}left(2x-5right)dfrac{3}{2}
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tìm x , biết:
a) \(x\) : \(4\dfrac{1}{3}\) = -2,5 b) \(\dfrac{3}{5}x\) + \(\dfrac{1}{4}\) = \(\dfrac{1}{10}\)
c) \(2\dfrac{7}{9}\) \(-\) \(\dfrac{12}{13}x\) = \(\dfrac{7}{9}\) d)\(\dfrac{-2}{3}-\dfrac{1}{3}\)\(\left(2x-5\right)=\dfrac{3}{2}\)
a, \(x\) : \(\dfrac{13}{3}\) = -2,5
\(x\) = -2,5 . \(\dfrac{13}{3}\)
\(x\) = \(\dfrac{65}{6}\)
b,\(\dfrac{3}{5}\)\(x\) = \(\dfrac{1}{10}-\)\(\dfrac{1}{4}\)
\(\dfrac{3}{5}x\) = \(\dfrac{-3}{20}\)
\(x\) = \(\dfrac{-3}{20}\) : \(\dfrac{3}{5}\)
\(x\) = \(\dfrac{-1}{4}\)
c, \(\dfrac{25}{9}-\dfrac{12}{13}x=\dfrac{7}{9}\)
\(\dfrac{12}{13}x\)\(=\dfrac{25}{9}-\dfrac{7}{9}\)
\(\dfrac{12}{13}x=2\)
\(x=2:\dfrac{12}{13}\)
\(x=\dfrac{13}{6}\)
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Tìm x biết: a) x + \(\dfrac{2}{3}=\dfrac{4}{27}\) b) \(\dfrac{3}{4}x-\dfrac{7}{3}=\dfrac{1}{4}x+\dfrac{1}{6}\)
c) \(\dfrac{13}{10}x-\dfrac{5}{2}=\dfrac{7}{2}\) d) (3\(x\) + 2) \(\left(\dfrac{-2}{5}x-7\right)=0\)
a: x=4/27-2/3=4/27-18/27=-14/27
b: =>3/4x-1/4x=1/6+7/3
=>1/2x=1/6+14/6=5/2
hay x=5
c: =>13/10x=7/2+5/2=6
=>x=13/10:6=13/60
d: (3x+2)(-2/5x-7)=0
=>3x+2=0 hoặc 2/5x+7=0
=>x=-2/3 hoặc x=-35/2
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a: x=4/27-2/3=4/27-18/27=-14/27
b: =>3/4x-1/4x=1/6+7/3
=>1/2x=1/6+14/6=5/2
hay x=5
c: =>13/10x=7/2+5/2=6
=>x=13/10:6=13/60
d: (3x+2)(-2/5x-7)=0
=>3x+2=0 hoặc 2/5x+7=0
=>x=-2/3 hoặc x=-35/2
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Xem thêm câu trả lời
tìm x:
a) \(-8:\left(4\dfrac{1}{5}x+\dfrac{3}{10}\right)=4\dfrac{4}{9}\)
b) \(4\dfrac{2}{3}-\left(\dfrac{3}{5}:x\right)=-20\%\)
c) \(\left(\dfrac{13}{10}x-15\right).-\dfrac{5}{14}=3\)
d) \(\left(5,5x-44\right):\left(-\dfrac{3}{2}\right)=30\)
e) \(\dfrac{11}{14}:\left(2x+\dfrac{5}{7}\right)=-\dfrac{11}{18}\)
\(a.-8:\left(4\dfrac{1}{5}x+\dfrac{3}{10}\right)=4\dfrac{4}{9}\)
\(4\dfrac{1}{5}x+\dfrac{3}{10}=\left(-8\right):4\dfrac{4}{9}\)
\(4\dfrac{1}{5}x+\dfrac{3}{10}=\dfrac{-9}{5}\)
\(4\dfrac{1}{5}x=\dfrac{-9}{5}-\dfrac{3}{10}\)
\(4\dfrac{1}{5}x=\dfrac{-21}{10}\)
\(x=\dfrac{-21}{10}:\dfrac{21}{5}\)
\(x=\dfrac{-1}{2}\)
Vay \(x=\dfrac{-1}{2}\).
\(b.4\dfrac{2}{3}-\left(\dfrac{3}{5}:x\right)=-20\%\)
\(\dfrac{14}{3}-\left(\dfrac{3}{5}:x\right)=\dfrac{-1}{5}\)
\(\dfrac{3}{5}:x=\dfrac{14}{3}-\dfrac{-1}{5}\)
\(\dfrac{3}{5}:x=\dfrac{73}{15}\)
\(x=\dfrac{3}{5}:\dfrac{73}{15}\)
\(x=\dfrac{9}{73}\)
Vay \(x=\dfrac{9}{73}\).
Câu c; d; e tương tự nhé.
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Viết các số đo thời gian sau đây dưới dạng hỗn số và phân số với đơn vị là giờ:
1h15ph ; 2h20ph ; 3h12ph
Tính
6dfrac{3}{8}+5dfrac{1}{2} ; 5dfrac{3}{7}-2dfrac{3}{7} ; -5dfrac{1}{7}+3dfrac{2}{5} ; -2dfrac{1}{3}-1dfrac{2}{7}
tìm x biết
0,5x-dfrac{2}{3}xdfrac{7}{12} ; x: 4dfrac{1}{3}-2,5 ; 5,5xdfrac{13}{15} ; left(dfrac{3x}{7}+1right):-4dfrac{-1}{28}
Bài 4: Một người đi xe máy đoạn đường AB với vận tốc 26dfrac{1}{4}km/h hết 2,4h.Lúc về, người ấy đi với vận tố...
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Viết các số đo thời gian sau đây dưới dạng hỗn số và phân số với đơn vị là giờ:
1h15ph ; 2h20ph ; 3h12ph
Tính
\(6\dfrac{3}{8}+5\dfrac{1}{2}\) ; \(5\dfrac{3}{7}-2\dfrac{3}{7}\) ; \(-5\dfrac{1}{7}+3\dfrac{2}{5}\) ; \(-2\dfrac{1}{3}-1\dfrac{2}{7}\)
tìm x biết
0,5x-\(\dfrac{2}{3}\)x=\(\dfrac{7}{12}\) ; x: \(4\dfrac{1}{3}=-2,5\) ; 5,5x=\(\dfrac{13}{15}\) ; \(\left(\dfrac{3x}{7}+1\right):-4=\dfrac{-1}{28}\)
Bài 4: Một người đi xe máy đoạn đường AB với vận tốc 26\(\dfrac{1}{4}\)km/h hết 2,4h.Lúc về, người ấy đi với vận tốc 30km/h. Tính thời gian người ấy đi từ B đến A
Bài 5: Tìm y biết
y+30%y=-1,3 ; y-25%y=\(\dfrac{1}{2}\) ; 3\(\dfrac{1}{3}\)y+16\(\dfrac{3}{4}\)=-13,25
Tính một cách hợp lí
\(4\dfrac{3}{4}+(-0,37)+\dfrac{1}{8}+\left(-1,28\right)+\left(-2,5\right)+3\dfrac{1}{2}\)
Bài 4: 26 \(\dfrac{1}{4}\)= 26, 25 . Quãng đương là 26,25 . 2,4 = 63 km.
Thời gian đi từ B đến A là : 63 : 30 = 2,1 h
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tìm x biết:
a) \(5^x.\left(5^3\right)^2=625\)
b)\(\left(\dfrac{12}{15}\right)^x=\left(\dfrac{5}{3}\right)^{-5}-\left(-\dfrac{3}{5}\right)^4\)
c)\(\left(-\dfrac{3}{4}\right)^{3x-1}=\dfrac{256}{81}\)
d)\(172x^2-7^9:98^3=2^{-3}\)
Tìm $x$, biết :
a) $\left(\dfrac{1}{2}+1,5\right) \cdot x=\dfrac{1}{5}$
b) $\left(-1 \dfrac{3}{5}+x\right): \dfrac{12}{13}=2 \dfrac{1}{6}$
c) $\left(x: 2 \dfrac{1}{3}\right) \cdot \dfrac{1}{7}=\dfrac{-3}{8}$
d) $\dfrac{-4}{7} \cdot x+\dfrac{7}{5}=\dfrac{1}{8}:\left(-1 \dfrac{2}{3}\right)$
\(a)\left(\dfrac{1}{2}+1,5\right)x=\dfrac{1}{5}\)
\(\Rightarrow2x=\dfrac{1}{5}\)
\(\Rightarrow x=\dfrac{1}{10}\)
\(b)\left(-1\dfrac{3}{5}+x\right):\dfrac{12}{13}=2\dfrac{1}{6}\)
\(\Leftrightarrow-\dfrac{8}{5}+x=\dfrac{13}{6}.\dfrac{12}{13}\)
\(\Leftrightarrow-\dfrac{8}{5}+x=2\)
\(\Leftrightarrow x=\dfrac{18}{5}\)
\(c)\left(x:2\dfrac{1}{3}\right).\dfrac{1}{7}=-\dfrac{3}{8}\)
\(\Leftrightarrow x:\dfrac{7}{3}=-\dfrac{3}{8}:\dfrac{1}{7}\)
\(\Leftrightarrow x=-\dfrac{21}{8}.\dfrac{7}{3}\)
\(\Leftrightarrow x=-\dfrac{49}{8}\)
\(d)-\dfrac{4}{7}x+\dfrac{7}{5}=\dfrac{1}{8}:\left(-1\dfrac{2}{3}\right)\)
\(\Leftrightarrow-\dfrac{4}{7}x+\dfrac{7}{5}=-\dfrac{3}{40}\)
\(\Leftrightarrow-\dfrac{4}{7}x=-\dfrac{59}{40}\)
\(\Leftrightarrow x=\dfrac{413}{160}\)
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Tìm x biết :
a, 0,5x - 2/3x=7/12
b, x:4 và 1/3=-2,5
c, 5,5x=13/15
d, ( 3x/7+1):(-4)=-1/28
a: =>1/2x-2/3x=7/12
=>-1/6x=7/12
hay x=-7/2
b: \(\Leftrightarrow x=-\dfrac{5}{2}\cdot\dfrac{13}{3}=\dfrac{-65}{6}\)
c: =>x=13/15:11/2=26/165
d: =>3/7x+1=1/7
=>3/7x=-6/7
hay x=-2
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