![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(\dfrac{x-3}{5-x}=\dfrac{5}{7}\left(x\ne5\right)\)
=>7(x-3)=5(5-x)
=>7x-21=25-5x
=>12x=46
=>x=23/6
b: \(\dfrac{x-2}{x-1}=\dfrac{x+4}{x+7}\)(ĐKXĐ: \(x\notin\left\{1;-7\right\}\))
=>(x-2)(x+7)=(x+4)(x-1)
=>\(x^2+5x-14=x^2+3x-4\)
=>5x-14=3x-4
=>2x=10
=>x=5(nhận)
![](https://rs.olm.vn/images/avt/0.png?1311)
5) // 3x + 1 / - 5 / = 2
=> / 3x + 1 / -5 = 2 hoặc -2
TH1: / 3x + 1 / - 5 = 2 => / 3x + 1 / = 2 + 5 = 7 => 3x + 1 = 7 hoặc -7
*1: 3x + 1 = -7 => 3x = -7 - 1 = -8 => x = -8/3
*2: 3x + 1 = 7 => 3x = 7 - 1 = 6 => x = 6 : 3 = 2
TH2: / 3x + 1 / - 5 = -2 => / 3x + 1/ = -2 + 5 = 3 => 3x + 1 = 3 hoặc -3
*1: 3x + 1 = 3 => 3x = 3 - 1 = 2 => x = 2/3
*2: 3x + 1 = -3 => 3x = -3 - 1 = -4 => x = -4/3
Vậy x thuộc { -8/3 ; 2 ; 2/3 ; -4/3 }
7) 3/2 + 4/5 /x - 3/4 / = 7/4
=> 4/5 / x - 3/4 / = 7/4 - 4/5
=> 4/5 / x - 3/4 / = 19/20
=> / x - 3/4 / = 19/20 : 4/5
=> / x - 3/4 / = 19/16
=> / x - 3/4 / = 19/16 hoặc -19/16
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{x+4}{5}+\frac{x+2}{7}=\frac{x+5}{4}+\frac{x+7}{2}\)
\(\Rightarrow\left(\frac{x+4}{5}+1\right)+\left(\frac{x+2}{7}+1\right)=\left(\frac{x+7}{2}+1\right)+\left(\frac{x+2}{7}+1\right)\)
\(\Rightarrow\frac{x+9}{5}+\frac{x+9}{7}=\frac{x+9}{4}+\frac{x+9}{2}\)
\(\Rightarrow\frac{x+9}{2}+\frac{x+9}{4}-\frac{x+9}{7}-\frac{x+9}{5}=0\)
\(\Rightarrow\left(x+9\right)\left(\frac{1}{2}+\frac{1}{4}-\frac{1}{5}-\frac{1}{7}\right)=0\)
vì \(\frac{1}{2}+\frac{1}{4}-\frac{1}{5}-\frac{1}{7}\ne0\Rightarrow x+9=0\)
=>x=-9
vậy x=-9
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a) \(=\dfrac{8}{15}\left(\dfrac{7}{13}+\dfrac{6}{13}\right)=\dfrac{8}{15}.1=\dfrac{8}{15}\)
b) \(=\dfrac{3.3-7-2.4}{12}=-\dfrac{6}{12}=-\dfrac{1}{2}\)
Bài 2:
\(\dfrac{x}{2,7}=-\dfrac{2}{3,6}\Rightarrow x=\dfrac{\left(-2\right).2,7}{3,6}\Rightarrow x=-\dfrac{3}{2}\)
Bài 3:
\(\dfrac{x}{2}=\dfrac{y}{5}=\dfrac{x+y}{2+5}=-\dfrac{21}{7}=-3\)
\(\Rightarrow\left\{{}\begin{matrix}x=\left(-3\right).2=-6\\y=\left(-3\right).5=-10\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left|\frac{3}{2}x+\frac{1}{2}\right|=\left|4x-1\right|\)
\(\Rightarrow\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\\frac{3}{2}x+\frac{1}{2}=-4x+1\end{cases}}\Rightarrow\orbr{\begin{cases}4x-\frac{3}{2}x-1=\frac{1}{2}\\-4x-\frac{3}{2}x+1=\frac{1}{2}\end{cases}}\Rightarrow\orbr{\begin{cases}\frac{5}{2}x=\frac{3}{2}\\-\frac{11}{2}x=-\frac{1}{2}\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{3}{5}\\x=\frac{1}{11}\end{cases}}\)
phần b ở đề bài mình ghi sai, là bằng 0 chứ ko phải bằng 10
![](https://rs.olm.vn/images/avt/0.png?1311)