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\(0,4.x-\frac{1}{5}.x=\frac{3}{4}\)
<=>\(x.\left(0,4-\frac{1}{5}\right)=\frac{3}{4}\)
<=>\(x.\frac{1}{5}=\frac{3}{4}\)
<=>\(x=\frac{3}{4}:\frac{1}{5}\)
<=>\(x=\frac{15}{4}\)
vậy \(x=\frac{15}{4}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
0,4x-1/5=3/4
0.4x=3/4+1/5
0.4x=19/20
x=19/20:0,4
x=19/8=2,375
k mik nha ^o^
\(0,4x-\frac{1}{5}=\frac{3}{4}\)
\(0,4x=\frac{19}{20}\)
\(x=\frac{19}{8}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a)
\(A=\dfrac{-5}{6}\cdot\dfrac{3}{10}\\ =\dfrac{\left(-5\right)\cdot3}{6\cdot10}\\ =\dfrac{-1}{4}\)
b)
\(B=\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{12}\\ =\dfrac{4}{12}-\dfrac{3}{12}+\dfrac{1}{12}\\ =\dfrac{4-3+1}{12}\\ =\dfrac{1}{6}\)
Bài 2:
\(A=\left(\dfrac{-1}{5}\right)\cdot\dfrac{15}{4}+\left|\dfrac{4}{5}-\dfrac{14}{5}\right|:\dfrac{8}{3}\\ =\left(\dfrac{-1}{5}\right)\cdot\dfrac{15}{4}+\left|\dfrac{-10}{5}\right|\cdot\dfrac{3}{8}\\ =\left(\dfrac{-1}{5}\right)\cdot\dfrac{15}{4}+2\cdot\dfrac{3}{8}\\ =\dfrac{-3}{4}+\dfrac{3}{4}\\ =0\)
\(B=\left(\dfrac{-1}{2}\right)^2:1\dfrac{3}{8}+25\%\cdot\dfrac{3}{11}\\ =\left(\dfrac{-1}{2}\right)^2:\dfrac{11}{8}+\dfrac{3}{4}\cdot\dfrac{3}{11}\\ =\dfrac{1}{4}\cdot\dfrac{8}{11}+\dfrac{3}{4}\cdot\dfrac{3}{11}\\ =\dfrac{8}{44}+\dfrac{9}{44}\\ =\dfrac{17}{44}\)
\(C=\dfrac{-8}{5}+0,6+\left|\dfrac{-1}{2}\right|+\dfrac{1}{2}\\ =\dfrac{-8}{5}+\dfrac{3}{5}+\dfrac{1}{2}+\dfrac{1}{2}\\ =\left(\dfrac{-8}{5}+\dfrac{3}{8}\right)+\left(\dfrac{1}{2}+\dfrac{1}{2}\right)\\ =\left(-1\right)+1\\ =0\)
\(D=\dfrac{-5}{9}\cdot\dfrac{2}{13}+\dfrac{-5}{9}:\dfrac{13}{11}+1\dfrac{5}{9}\\ =\dfrac{-5}{9}\cdot\dfrac{2}{13}+\dfrac{-5}{9}\cdot\dfrac{11}{13}+\dfrac{14}{9}\\ =\dfrac{-5}{9}\cdot\left(\dfrac{2}{13}+\dfrac{11}{13}\right)+\dfrac{14}{9}\\ =\dfrac{-5}{9}\cdot1+\dfrac{14}{9}\\ =\dfrac{-5}{9}+\dfrac{14}{9}\\ =1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
0,25x -0,4x = 1
x(0,25 - 0,4) = 1
-0,15x =1
x = 1 : (-0,15)
x = - 20/3
![](https://rs.olm.vn/images/avt/0.png?1311)
\(60\%.x-0,4.x+x:3=2\)
\(\dfrac{3}{5}.x-\dfrac{2}{5}.x+\dfrac{1}{3}.x=2\)
\(x\left(\dfrac{3}{5}-\dfrac{2}{5}+\dfrac{1}{3}\right)=2\)
\(x.\dfrac{8}{15}=2\)
\(x=2:\dfrac{8}{15}\)
\(x=\dfrac{15}{4}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
60%x + 0,4x + x:3 = 2
\(\frac{3}{5}x+\frac{2}{5}x+\frac{1}{3}x=2\)
\(\left(\frac{3}{5}+\frac{2}{5}+\frac{1}{3}\right)x=2\)
\(\frac{4}{3}x=2\)
\(x=2:\frac{4}{3}\)
\(x=\frac{3}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(14:\frac{0,4x+0,6}{x}=7\)
\(\frac{0,4x+0,6}{x}=2\)
0,4x + 0,6 = 2.x
2x - 0,4x = 0,6
1,6x = 0,6
x = 0,375
b) \(\left(160\%+\frac{2}{3}x-x\right).12=660\)
\(\left(160\%+\frac{2}{3}x-x\right)=55\)
\(x\left(\frac{2}{3}-1\right)=53,4\)
\(-\frac{1}{3}x=\frac{267}{5}\)
\(x=\frac{267}{5}.\frac{3}{-1}\)
\(x=-160,2\)
c) \(1:\frac{1.2.3.4.....31}{2.2.2.3.2.4.....2.32}=2^x\)
\(1:\frac{1.2.3.4.....31}{2^{31}.2.3.4.....31.2^5}=2^x\)
\(1:\frac{1}{2^{36}}=2^x\)
\(2^{36}=2^x\)
\(x=36\)
\(0,4.x-\frac{1}{5}.x=\frac{3}{4}\)
<=> \(x.\left(0,4-\frac{1}{5}\right)=\frac{3}{4}\)
<=> \(x.\frac{1}{5}=\frac{3}{4}\)
<=> \(x=\frac{3}{4}:\frac{1}{5}\)
<=> \(x=\frac{15}{4}\)
kết luận : \(x=\frac{15}{4}\)