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a ) \(\left(\frac{2}{5}-x\right):1\frac{1}{3}+\frac{1}{2}=-4\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}+\frac{1}{2}=-4\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}=-4-\frac{1}{2}\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}=-\frac{9}{2}\)
\(\frac{2}{5}-x=-\frac{9}{2}.\frac{4}{3}\)
\(\frac{2}{5}-x=-3\)
\(x=\frac{2}{5}-\left(-3\right)\)
\(x=\frac{2}{5}+3\)
\(x=\frac{3}{5}-\frac{15}{5}\)
\(x=-\frac{12}{5}\)
Vay \(x=-\frac{12}{5}\)
b ) \(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(1+\frac{2}{5}+\frac{2}{3}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(\frac{15}{15}+\frac{6}{15}+\frac{10}{15}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(\frac{15+6+10}{15}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\frac{31}{15}=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right)=-\frac{5}{4}.\frac{31}{15}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right)=-\frac{1}{4}.\frac{31}{3}\)
\(-3+\frac{3}{x}-\frac{1}{3}=-\frac{31}{12}\)
\(-3+\frac{3}{x}=-\frac{31}{12}+\frac{1}{2}\)
\(-3+\frac{3}{x}=-\frac{31}{12}+\frac{6}{12}\)
\(-3+\frac{3}{x}=\frac{-25}{12}\)
\(\frac{3}{x}=\frac{-25}{12}+3\)
\(\frac{3}{x}=\frac{-25}{12}+\frac{36}{12}\)
\(\frac{3}{x}=\frac{5}{6}\)
\(\frac{18}{6x}=\frac{5x}{6x}\)
Đèn dây , bạn tự làm tiếp nhé , de rồi chứ
a) \(x:8=7:4\)
=> \(\frac{x}{8}=\frac{7}{4}\)
=> \(x.4=7.8\)
=> \(x.4=56\)
=> \(x=56:4\)
=> \(x=14\)
Vậy \(x=14.\)
b) \(\left(x+1\right):0,75=1,4:0,25\)
=> \(\left(x+1\right):0,75=5,6\)
=> \(\left(x+1\right)=5,6.0,75\)
=> \(x+1=4,2\)
=> \(x=4,2-1\)
=> \(x=3,2\)
Vậy \(x=3,2.\)
Mình chỉ làm 2 câu thôi nhé, bạn đăng nhiều quá.
Chúc bạn học tốt!
a) ko hiểu đề
b) \(3|x|-\frac{3}{5}-2|x|=\frac{5}{9}\)
\(\Leftrightarrow|x|-\frac{3}{5}=\frac{5}{9}\)
\(\Leftrightarrow|x|=\frac{52}{45}\)
\(\Leftrightarrow x=\pm\frac{52}{45}\)
a)
( 4x - 9 ) ( 2,5 + (-7/3) . x ) = 0
\(\Rightarrow\orbr{\begin{cases}4x-9=0\\2,5+\frac{-7}{3}x=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{9}{4}\\x=\frac{15}{14}\end{cases}}\)
P/s: đợi xíu làm câu b
b) \(\frac{1}{x\left(x+1\right)}\cdot\frac{1}{\left(x+1\right)\left(x+2\right)}\cdot\frac{1}{\left(x+2\right)\left(x+3\right)}-\frac{1}{x}=\frac{1}{2015}\)
\(\frac{1}{x}-\frac{1}{x+1}+\frac{1}{x+1}-\frac{1}{x+2}+\frac{1}{x+2}-\frac{1}{x+3}-\frac{1}{x}=\frac{1}{2015}\)
\(\frac{-1}{x+3}=\frac{1}{2015}\)
\(\Leftrightarrow x+3=-2015\)
\(\Leftrightarrow x=-2018\)
Vậy,.........
Bài 1 khó hiểu quá
Bài 2:
a)2,5:7,5=x:\(\frac{3}{5}\)
x:\(\frac{3}{5}\)=\(\frac{1}{3}\)
x=\(\frac{1}{3}.\frac{3}{5}\)
\(x=\frac{1}{5}\)
Vậy \(x=\frac{1}{5}\)
b)\(2\frac{2}{3}:x=1\frac{7}{9}:0,2\)
\(2\frac{2}{3}:x=\frac{80}{9}\)
\(x=2\frac{2}{3}:\frac{80}{9}\)
\(x=\frac{3}{10}\)
Vậy \(x=\frac{3}{10}\)
c)\(\frac{x}{5}=\frac{4}{10}\)
\(\Rightarrow x.10=4.5\)
\(\Rightarrow x.10=20\)
\(\Rightarrow x=2\)
Vậy x=2
d)\(\frac{18}{7}=\frac{x}{21}\)
\(\Rightarrow x.7=18.21\)
\(\Rightarrow x.7=378\)
\(\Rightarrow x=54\)
Vậy x=54
e)\(\frac{x}{6}=\frac{24}{x}\)
\(\Rightarrow x.x=24.6\)
\(\Rightarrow x^2=144=12^2=\left(-12\right)^2\)
Do đó:x=12;-12
Vậy x=-12;12
Bài 2,
a, 2,5 : 7,5 = x : \(\frac{3}{5}\)
\(\frac{1}{3}\) = x : \(\frac{3}{5}\)
x = \(\frac{1}{3}\) . \(\frac{3}{5}\)
x = \(\frac{1}{5}\)
b , \(2\frac{2}{3}\) : x = \(1\frac{7}{9}\) : 0,2
\(\frac{8}{3}\) : x = \(\frac{16}{9}\) : 0.2
\(\frac{8}{3}\) : x = \(\frac{80}{9}\)
x = \(\frac{8}{3}\) :\(\frac{80}{9}\)
x = 0,3
c, \(\frac{x}{5}\) = \(\frac{4}{10}\)
\(\Rightarrow\) 10x = 4.5 = 20
x = 20 : 10
x = 2
d,\(\frac{18}{7}\) = \(\frac{x}{21}\)
\(\Rightarrow\) 18.21 = 7x
378 = 7.x
x = 378 : 7
x = 54
e,\(\frac{x}{6}\) = \(\frac{24}{x}\)
\(\Rightarrow\) x2 = 6 . 24
x2 = 144
\(\Rightarrow\) x = \(\pm\) 12