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Lời giải:
a.
$0< x< \frac{1}{4}+\frac{4}{5}$
$\Rightarrow 0< x< \frac{21}{20}$ hay $0< x< 1,05$
$\Rightarrow x=1$
b.
$\frac{4}{7}+\frac{3}{7}< x< \frac{5}{3}+\frac{2}{3}$
$\Rightarrow 1< x< \frac{7}{3}$
$\Rightarrow x=2$
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a, 35 - \(x\) < 35 - 5
35 - \(x\) < 30
\(x\) < 35 - 30
\(x\) < 5
\(x\) = 1; 2; 3; 4; 5
b, \(x\) - 10 < 35 - 10
\(x\) - 10 < 15
\(x\) < 15 + 10
\(x\) < 25
\(x\) = 0; 1; 2; 3; 4; 5; ....;24
c, \(x\) - 10 < 45
\(x\) < 45 + 10
\(x\) < 55
\(x\) = 0; 1; 2; 3; 4;...;54
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a)4/9 : x/6 = 2/3
x/6 = 4/9 : 2/3
x/6 = 2/3 = 4/6
vậy x = 4
b)x/5 x 3/7 = 9/35
x/5 = 9/35 : 3/7
x/5 = 3/5
vậy x = 3
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\(\frac{x}{50}\)= \(\frac{1}{10}\)
\(\frac{x}{50}\)= \(\frac{5}{50}\)
=> x= 5
Vậy x=5
\(\frac{35}{x}\)= \(\frac{5}{6}\)
\(\frac{35}{x}\)= \(\frac{35}{42}\)
=> x=42
Vậy x=42
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1 < x/5 < 8/5
=> 5/5 < x/5 < 8/5
=> 5 < x < 8
=> x = 6 hoặc 7
1 < 10/x < 2
=> 10/10 < 10/x < 10/5
=> 10 > x > 5
=> x = 6 ; 7 ; 8 hoặc 9
Ủng hộ mk nha ☆_☆★_★^_-
- x có thể bằng 6 hoặc 7
- x nằm trong khoảng từ 1,2,3,4
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+2xy-y=0\\ \Leftrightarrow x\left(2y+1\right)-y=0\\ \Leftrightarrow2x\left(2y+1\right)-2y-1+1=0\\ \Leftrightarrow2x\left(2y+1\right)-\left(2y+1\right)=-1\\ \Leftrightarrow\left(2x-1\right)\left(2y+1\right)=-1\)
Vì \(x,y\in N\Rightarrow\left\{{}\begin{matrix}2x-1\in Z,2y+1\in N\\2x-1,2y+1\inƯ\left(-1\right)\end{matrix}\right.\)
Ta có bảng:
2x-1 | -1 |
2y+1 | 1 |
x | 0 |
y | 0 |
Vậy \(\left(x,y\right)\in\left(0;0\right)\)
x-35-120=0
x-35=120
x=120+35
x=155