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![](https://rs.olm.vn/images/avt/0.png?1311)
làm cho 1 cái những cái sau tương tự mà lm nha bạn
\(\frac{x}{5}=-\frac{6}{7}\)
\(=>7x=-6\cdot5\)
\(7x=-30\)
\(x=-\frac{30}{7}\)
\(\frac{x}{2}=-\frac{8}{-x}\)
\(=>\frac{x}{2}=\frac{8}{x}\)
\(=>xx=8\cdot2\)
\(x^2=16\)
\(=>x\in\left\{-4;4\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(\frac{x+3}{x+5}=7\Leftrightarrow x+3=7\left(x+5\right)\)
\(\Leftrightarrow x+3=7x+35\)
\(\Leftrightarrow-6x=32\)
\(\Leftrightarrow x=-\frac{16}{3}\)
b)\(\frac{2x-1}{3x+5}=-\frac{2}{3}\)
\(\Leftrightarrow3\left(2x-1\right)=-2\left(3x+5\right)\)
\(\Leftrightarrow6x-3=-6x-10\)
\(\Leftrightarrow12x=-7\)
\(\Leftrightarrow x=-\frac{7}{12}\)
c)\(\frac{x+1}{4}=\frac{9}{x+1}\Leftrightarrow\left(x+1\right)^2=36\)
\(\Leftrightarrow\left(x+1\right)^2=6^2\)
\(\Leftrightarrow\orbr{\begin{cases}x+1=6\\x+1=-6\end{cases}\Leftrightarrow\orbr{\begin{cases}x=5\\x=-7\end{cases}}}\)
d)\(\frac{6x-1}{2x+3}=\frac{3x}{x+2}\)
\(\Leftrightarrow\left(6x-1\right)\left(x+2\right)=3x\left(2x+3\right)\)
\(\Leftrightarrow6x^2+12x-x-2=6x^2+9x\)
\(\Leftrightarrow2x=2\Leftrightarrow x=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(\frac{x+1}{5}+\frac{x+3}{4}=\frac{x+5}{3}+\frac{x+7}{2}\)
\(\Leftrightarrow\frac{12\left(x+1\right)}{60}+\frac{15\left(x+3\right)}{60}=\frac{20\left(x+5\right)}{60}+\frac{30\left(x+7\right)}{60}\)
\(\Leftrightarrow12x+12+15x+45=20x+100+30x+210\)
\(\Leftrightarrow27x+57=50x+310\)
\(\Leftrightarrow27x+57-50x-310=0\)
\(\Leftrightarrow-23x-253=0\)
\(\Leftrightarrow x=-\frac{253}{23}\)
b)Tự làm
![](https://rs.olm.vn/images/avt/0.png?1311)
mk cung hoc lop 7 nhung cai bai do ma ko lam dc thi chet di
a) 2/x+7=x+7/32
<=> (x+7)^2=64
=> x+7=8 hoặc x+7=-8
=> x=-1 hoặc x=-15
b) - (x+5)^2= (x-2).(x+8)
<=> -(x+5)^2=x^2+8x-2x-16
<=> - (x+5)^2 =(x-4)^2
+> Không có giá trị x thỏa mãn
a. ĐK: x\(\ne\)-7
2.32=(x+7)2
<=> 64=x2+ 14x+ 49
<=>x2+ 14x- 15=0
<=>x2+ 15x- x- 15=0
<=>(x-1)(x+15)=0
\(\Leftrightarrow\hept{\begin{cases}x=1\\x=-15\end{cases}}\)
b, ĐK: x\(\ne\)-5;-8
(x-2)(x+8)=(x-5)(x+5)
<=>x2+ 6x- 16=x2- 25
<=>6x+9=0
\(\Leftrightarrow x=-\frac{3}{2}\)