0,4 x x = 1/2
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
1. $=12,5\times 5+12,5\times 4+12,5$
$=12,5\times (5+4+1)=12,5\times 10=125$
2.
$=(0,4\times 0,25)\times (2\times 50)$
$=0,1\times 100=10$
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(0,4x-2\right)-\left(1,5x+1\right)\) \(\left(-4x-0,8\right)\)\(=3,6\)
<=>\(\left(0,4x-2\right)-\)\(\left(-6x^2-1,2x-4x-0,8\right)\)\(=3,6\)
<=> \(0,4x-2+6x^2+1,2x\)\(+4x+0,8=3,6\)
<=> \(6x^2+5,6x-1,2=3,6\)
<=> \(6x^2+5,6x-4,8=0\)
<=>
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{7}{2}\) : \(\dfrac{2}{5}\) = x : \(\dfrac{8}{7}\)
x : \(\dfrac{8}{7}\) = \(\dfrac{7}{2}\) : \(\dfrac{2}{5}\)
x : \(\dfrac{8}{7}\) = \(\dfrac{35}{4}\)
x = \(\dfrac{35}{4}\) . \(\dfrac{8}{7}\)
x = 10
![](https://rs.olm.vn/images/avt/0.png?1311)
`x+1/2=3/4 : 3/2`
`=>x+1/2 = 3/4 . 2/3`
`=>x+1/2 = 1/2`
`=>x=1/2-1/2`
`=>x=0`
Vậy `x=0`
__
`2,4xx y = 6/5 xx 0,4`
`=> 24/10 xx y = 6/5 xx 4/10`
`=> 12/5 xx y = 6/5 xx 2/5`
`=> 12/5 xx y = 12/25`
`=> y = 12/25 : 12/5`
`=> y = 12/25 . 5/12`
`=> y = 5/25`
`=> y = 1/5`
Vậy `y=1/5`
`#QiN`
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(1\frac{2}{7} = 1 + \frac{2}{7} = \frac{9}{2}\)
\(\begin{array}{l}x:1\frac{2}{7} = - 3,5\\x:\frac{9}{7} = - \frac{7}{2}\\x = - \frac{7}{2}.\frac{9}{7}\\x = - \frac{9}{2}\end{array}\)
b) \(0,4.x - \frac{1}{5}.x = \frac{3}{4}\)
\(\begin{array}{l}\frac{2}{5}.x - \frac{1}{5}.x = \frac{3}{4}\\\left( {\frac{2}{5} - \frac{1}{5}} \right).x = \frac{3}{4}\\\frac{1}{5}.x = \frac{3}{4}\\x = \frac{3}{4}:\frac{1}{5}\\x = \frac{3}{4}.5\\x = \frac{{15}}{4}\end{array}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\left(2+4+6+...+98\right)\left(6-6\right)\left(\dfrac{1}{2}+\dfrac{1}{4}+...+\dfrac{1}{512}\right)\)
=0
![](https://rs.olm.vn/images/avt/0.png?1311)
a . ( 2,75 + 125% ) x 5/2 - 0,4 x 2 : 8% b . ( 1/3 - 25% ) : 50% + ( 1/3 + 0,25 ) x 1/7
= ( 2,75 + 1,25 ) x 2,5 - 0,4 x 2 : 0,08 = ( 1/3 - 1/4 ) : 1/2 + ( 1/3 + 1/4 ) x 1/7
= 4 x 2,5 - 0,4 x 2 : 0,8 = 1/12 : 1/2 + 1/12 x 1/7
= 10 - 0,8 : 0,8 = 1/12 x 2 + 1/12 x 1/7
= 10 - 1 = 1/12 x ( 2 + 1/7 )
= 9 = 1/12 x 15/7 = 5/28
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(=\dfrac{5}{4}\cdot\dfrac{2}{5}\cdot\dfrac{17}{21}\cdot\dfrac{7}{34}=\dfrac{1}{2}\cdot\dfrac{1}{2}\cdot\dfrac{1}{3}=\dfrac{1}{12}\)
b: =>0,5^x(0,5+1)=1,5
=>0,5^x=1
=>x=0
c: =>x*0,05-0,25*x=-1,2
=>-0,3*x=-1,2
=>x=4
d: =>x-1=1 hoặc x-1=-1
=>x=0 hoặc x=2
e: =5+4=9
![](https://rs.olm.vn/images/avt/0.png?1311)
B)\(\frac{11}{2}+x=\frac{3}{2}-7\)
\(\frac{11}{2}+x=\frac{3}{2}-\frac{14}{2}\)
\(\frac{11}{2}+x=\frac{-11}{2}\)
\(x=\frac{-11}{2}-\frac{11}{2}\)
\(x=\frac{-22}{2}\)
\(x=-11\)
A)\(\frac{1}{3}x+\frac{2}{5}\left(x+1\right)=0\)
\(\frac{1}{3}x+\frac{2}{5}x+\frac{2}{5}=0\)
\(x\cdot\left(\frac{1}{3}+\frac{2}{5}\right)=0-\frac{2}{5}\)
\(x\cdot\left(\frac{5}{15}+\frac{6}{15}\right)=-\frac{2}{5}\)
\(x\cdot\frac{11}{15}=\frac{-2}{5}\)
\(x=\frac{-2}{5}:\frac{11}{5}\)
\(x=\frac{-2}{11}\)
nhớ k cho mình nha
a) 1/3 x + 0,4 ( x + 1 ) = 0
<=> 1/3 x + 0,4 . x + 0,4 . 1 = 0
<=> 1/3 x + 0,4 x + 0,4 = 0
<=> x. ( 1/3 + 0,4 ) + 0,4 = 0
<=> x. 11/15 + 0.4 = 0
<=> x. 11/15 = -2/5
<=> x = -2/5 : 11/15 = - 6/11
b) 1 1/2 + x = 3/2 -7
<=> 3/2 + x = -11/2
<=> x = -11/2 - 3/2
<=> x = -7 < GOOD LUCK >
x=1/2:0,4
x=5/4=1,25
Rep tin nhắn :))