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a: \(\Leftrightarrow\left(x-\dfrac{2}{5}\right):\dfrac{3}{2}=-\dfrac{5}{4}+\dfrac{5}{2}=\dfrac{5}{4}\)
\(\Leftrightarrow x-\dfrac{2}{5}=\dfrac{5}{4}\cdot\dfrac{3}{2}=\dfrac{15}{8}\)
hay x=91/40
b: \(\Leftrightarrow\left(2.5x-3.6\right)=-1\cdot\dfrac{12}{7}=\dfrac{-12}{7}\)
=>2,5x=66/35
hay x=132/175
c: \(\Leftrightarrow\left(\dfrac{15}{4}-2x\right)=\dfrac{19}{9}:\dfrac{4}{3}=\dfrac{19}{9}\cdot\dfrac{3}{4}=\dfrac{19}{12}\)
=>2x=15/4-19/12=45/12-19/12=26/12
=>x=13/12
1,
\(\dfrac{6}{7}\) + \(\dfrac{-5}{8}\) : (-5) -\(\dfrac{3}{16}\) . \(\left(-2\right)^2\)
= \(\dfrac{6}{7}\) + \(\dfrac{-5}{8}\) . \(\dfrac{-1}{5}\) - \(\dfrac{3}{16}\) . 4
= \(\dfrac{6}{7}\) + \(\dfrac{1}{8}\) - \(\dfrac{3}{4}\)
= \(\dfrac{48}{56}\) + \(\dfrac{7}{56}\) - \(\dfrac{42}{56}\)
= \(\dfrac{13}{56}\)
3,
a,\(\dfrac{3}{5}\)x - \(\dfrac{7}{10}\)x = \(\dfrac{-1}{2}\)
x.(\(\dfrac{3}{5}\) - \(\dfrac{7}{10}\)) = \(\dfrac{-1}{2}\)
x.\(\dfrac{-1}{10}\)= \(\dfrac{-1}{2}\)
x =\(\dfrac{-1}{2}\):\(\dfrac{-1}{10}\)
x = 5
c, (2,5x - 3,6) : \(\dfrac{15}{7}\) = -1
( \(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\)) : \(\dfrac{15}{7}\) = -1
\(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\) = -1 . \(\dfrac{15}{7}\)
\(\dfrac{5}{2}\)x - \(\dfrac{18}{5}\) = \(\dfrac{-15}{7}\)
\(\dfrac{5}{2}\)x = \(\dfrac{-15}{7}\) + \(\dfrac{18}{5}\)
\(\dfrac{5}{2}\)x = \(\dfrac{51}{35}\)
x =\(\dfrac{51}{35}\) : \(\dfrac{5}{2}\)
x = \(\dfrac{102}{175}\)
Mình không biết có chỗ nào sai không nữa.
\(a,-\dfrac{13}{20}+x=\dfrac{-11}{15}\\ \Rightarrow x=\dfrac{-11}{15}+\dfrac{13}{20}\\ \Rightarrow x=-\dfrac{1}{12}\\ b,\left(x-3,5\right):3\dfrac{1}{2}-2,5=-1\dfrac{3}{4}\\ \Rightarrow\left(x-\dfrac{7}{2}\right):\dfrac{7}{2}-\dfrac{5}{2}=\dfrac{-7}{4}\\ \Rightarrow\left(x-\dfrac{7}{2}\right):\dfrac{7}{2}=\dfrac{3}{4}\\ \Rightarrow x-\dfrac{7}{2}=\dfrac{21}{8}\\ \Rightarrow x=\dfrac{49}{8}\)
a: =6-6=0
b: \(=\dfrac{-5}{4}:\dfrac{2-7}{8}+\dfrac{3}{2}\cdot\dfrac{2-5}{6}\)
\(=\dfrac{-5}{4}\cdot\dfrac{8}{-5}+\dfrac{3}{2}\cdot\dfrac{-3}{6}\)
\(=2+\dfrac{-9}{12}=2-\dfrac{3}{4}=\dfrac{5}{4}\)
c: \(=2,5\cdot\left(-0,65\right)+1,5\left(-0,3-0,35\right)=-0,65\cdot4=-2,6\)
\(x-2.5=\frac{1}{3}+\frac{2x}{3}\)
\(\Leftrightarrow\frac{3\left(x-2,5\right)}{3}=\frac{2x+1}{3}\)
\(\Leftrightarrow3x-7,5=2x+1\)
\(\Leftrightarrow x=8,5\)
c: Ta có: \(\dfrac{1}{3}-\dfrac{7}{8}x=\dfrac{1}{4}\)
\(\Leftrightarrow x\cdot\dfrac{7}{8}=\dfrac{1}{12}\)
\(\Leftrightarrow x=\dfrac{1}{12}\cdot\dfrac{8}{7}=\dfrac{2}{21}\)
d: Ta có: \(\dfrac{3}{2}x+\dfrac{1}{7}=\dfrac{7}{8}\cdot\dfrac{64}{49}\)
\(\Leftrightarrow x\cdot\dfrac{3}{2}=1\)
hay \(x=\dfrac{2}{3}\)
\(x\div4\frac{1}{3}=-2,5\)
\(\Leftrightarrow x\div\frac{13}{3}=\frac{-5}{2}\)
\(\Leftrightarrow x=\frac{-5}{2}.\frac{13}{3}\)
\(\Leftrightarrow x=\frac{-65}{6}\)
\(x\div\frac{-3}{5}=\frac{-10}{21}\)
\(\Leftrightarrow x=\frac{-10}{21}.\frac{-3}{5}\)
\(\Leftrightarrow x=\frac{30}{105}\)
\(\Leftrightarrow x=\frac{2}{7}\)
\(\frac{2}{3}x-\frac{1}{2}=\frac{1}{10}\)
\(\Leftrightarrow\frac{2}{3}x=\frac{1}{10}+\frac{1}{2}\)
\(\Leftrightarrow\frac{2}{3}x=\frac{6}{10}\)
\(\Leftrightarrow x=\frac{6}{10}\div\frac{2}{3}\)
\(\Leftrightarrow x=\frac{18}{20}\)
\(\Leftrightarrow x=\frac{9}{10}\)
\(\frac{1}{2}x+\frac{1}{2}=\frac{5}{2}\)
\(\Leftrightarrow\frac{1}{2}\left(x+1\right)=\frac{5}{2}\)
\(\Leftrightarrow\left(x+1\right)=\frac{5}{2}\div\frac{1}{2}\)
\(\Leftrightarrow\left(x+1\right)=5\)
\(\Leftrightarrow x=5-1\)
\(\Leftrightarrow x=4\)
-19/16
=-19/16 nha
~HT~
K cho mình nha cảm ơn các bn
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