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Tính phải k nhỉ?
`1)`
`2x + 3x + 5x`
`= (2 + 3 + 5)x`
`= 10x`
`2)`
`2.x - x + 3.x`
`= (2 - 1 + 3)x`
`= 4x`
`3)`
`9.x - 3 - 3.x`
`= (9 - 3)x - 3`
`= 6x - 3`
`4)`
Thiếu dấu, bạn bổ sung thêm
`5)`
`x - 0,2x - 0,1x`
`= (1 - 0,2 - 0,1)x`
`=0,7x`
`6)`
\(\dfrac{7}{2}x-\dfrac{1}{2}x=\left(\dfrac{7}{2}-\dfrac{1}{2}\right)x=3x\)
![](https://rs.olm.vn/images/avt/0.png?1311)
5/8 + 0,2 : |-x/4 + 2/5| = 3/2
0,2 : |-x/4 + 2/5| = 3/2 - 5/8
0,2 : |-x/4 + 2/5| = 7/8
|-x/4 + 2/5| = 7/8 . 0,2
|-x/4 + 2/5| = 7/40
\(\Rightarrow\orbr{\begin{cases}-\frac{x}{4}+\frac{2}{5}=\frac{7}{40}\\-\frac{x}{4}+\frac{2}{5}=-\frac{7}{40}\end{cases}\Rightarrow\orbr{\begin{cases}-\frac{x}{4}=-\frac{9}{40}\\-\frac{x}{4}=-\frac{23}{40}\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{9}{10}\\x=\frac{23}{10}\end{cases}}}\)
Báo cáo sai phạm
5/8 + 0,2 : |-x/4 + 2/5| = 3/2
0,2 : |-x/4 + 2/5| = 3/2 - 5/8
0,2 : |-x/4 + 2/5| = 7/8
|-x/4 + 2/5| = 7/8 . 0,2
|-x/4 + 2/5| = 7/40
⇒[
−x4 +25 =7/40 |
−x4 +25 =−7/40 |
⇒[
−x4 =−9/40 |
−x4 =−23/40 |
⇒[
x=9/10 |
x=2/310 |
![](https://rs.olm.vn/images/avt/0.png?1311)
\(0,5.\left[\frac{4}{3}.\left(-20\right)\right].0,75.\frac{8}{-35}\)
\(\frac{5}{10}.\left[\frac{4}{3}.\left(-20\right)\right].\frac{75}{100}.\frac{8}{-35}\)
\(=\frac{2}{5}.\left[\frac{4}{3}.\left(-20\right)\right].\frac{3}{4}.\frac{8}{-35}\)
\(=\left(\frac{4}{3}.\frac{3}{4}\right).\left[\frac{2}{5}.\frac{\left(-35\right)}{8}\right].\left(-20\right)\)
\(=1.\left(\frac{2}{1}.\frac{1}{4}\right).\left(-20\right)\)
\(=1.\frac{1}{2}.\left(-20\right)=-\frac{20}{2}=\frac{10}{1}=10\)
Mk ko chắc, bn tham khảo nha
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left|0,2x-\frac{3}{4}\right|=\left|-3x+0,1\right|\)
\(\Rightarrow0,2x-\frac{3}{4}=\hept{\begin{cases}-3x+0,1\\-\left(-3x+0,1\right)=3x-0,1\end{cases}}\)
\(\Rightarrow0,2x=\hept{\begin{cases}-3x+\frac{17}{20}\\3x+\frac{13}{20}\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}3,2x=\frac{17}{20}\\-2,8x=\frac{13}{20}\end{cases}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left|-\frac{2}{5}x-\frac{4}{3}\right|=\left|4x-\frac{5}{6}\right|\)
\(=-\frac{2x}{5}-\frac{4}{3}=4x-\frac{5}{6}\)
\(=-\frac{2x}{5}-\frac{4}{3}=-\left(4x-\frac{5}{6}\right)\)
\(=x=-\frac{5}{44};\frac{65}{108}\)
\(\Rightarrow x=\orbr{\begin{cases}x=-\frac{5}{44}\\x=\frac{65}{108}\end{cases}}\)
|−25 x−43 |=|4x−56 |
=−2x5 −43 =4x−56
=−2x5 −43 =−(4x−56 )
=x=−544 ;65108
⇒x=[
x=−544 |
x=65108 |
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left|\frac{5}{2}-3x\right|=\left|-2,5x-1,2\right|\)
\(\Rightarrow\left|\frac{5}{2}-3x\right|-\left|-2,5x-1,2\right|=0\)
\(\Rightarrow\left(\frac{5}{2}-3x\right)-\left(-2,5x-1,2\right)=0\)
\(\Rightarrow\frac{5}{2}-3x+2,5x+1,2=0\)
\(\Rightarrow\left(\frac{5}{2}+1,2\right)+\left(-3x+2,5x\right)=0\)
\(\Rightarrow\frac{37}{10}-0,5x=0\)
\(\Rightarrow0,5x=\frac{37}{10}\)
\(\Rightarrow x=\frac{37}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{7}{6}+\frac{5}{6}:5-\frac{3}{8}.\left(-3\right)^2\)
\(=\frac{7}{6}+\frac{5}{6}.\frac{1}{5}-\frac{3}{8}.9\)
\(=\frac{7}{6}+\frac{1}{6}-\frac{27}{8}\)
\(=\frac{8}{6}-\frac{27}{8}\)
\(=\frac{32}{24}-\frac{81}{24}\)
\(=\frac{-49}{24}\)
Chúc bạn học tốt !!!
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{4}{3}B=-1+\frac{3}{4}-\left(\frac{3}{4}\right)^2+...+\left(\frac{3}{4}\right)^{99}\)
\(B=-\frac{3}{4}+\left(\frac{3}{4}\right)^2-\left(\frac{3}{4}\right)^3+...+\left(\frac{3}{4}\right)^{100}\)
\(\Rightarrow\)\(\frac{7}{3}B=-1+\left(\frac{3}{4}\right)^{100}\Rightarrow B=\frac{\left(\frac{3}{4}\right)^{100}-1}{\frac{7}{3}}=\frac{3\left[\left(\frac{3}{4}\right)^{100}-1\right]}{7}\)
Như vầy đủ gọn chưa bạn?
TH1 : x < -1/30
=> 3/4 - 0,2 x = 3x + 0,1
=> 0,85 = 3,2 x
=> x = 64/17 > -1/30 ( loại )
TH2 : 15/4 > x > -1/30
=> 3/4 - 0,2 x = -3x + 1
=> -1/4 = -3,2x
=> x = 12,8 > 15/4 ( loại )
TH3 : x > 15/4
=> 0,2x - 3/4 = -3x + 0,1
=> - 3,2x = -0,85
=> x = 17/64 < 15/4 ( loại )
Vậy x thuộc rỗng
Sửa -1/30 thành 1/30 nha bạn , kết quả không đổi