3x+2 / 5x+7 = 3x-1 / 5x + 1
=> (3X+2)( 5X+1) = ( 3x-1) ( 5x+7)
=> 3x ( 5x+1) + 2( 5x+1) = 3x( 5x+7) - 5x - 7
15x^2 + 3x + 10x + 2 = 15x^2 + 21x - 5x - 7
15x^2+ 3x + 10x - 15x^2 - 21x + 5x = -7-2
13x - 16x = -9
-3x = -9
x = 3
Vậy x=3
Đúng 1000%
3x+2 / 5x+7 = 3x-1 / 5x + 1
=> (3X+2)( 5X+1) = ( 3x-1) ( 5x+7)
=> 3x ( 5x+1) + 2( 5x+1) = 3x( 5x+7) - 5x - 7
15x^2 + 3x + 10x + 2 = 15x^2 + 21x - 5x - 7
15x^2+ 3x + 10x - 15x^2 - 21x + 5x = -7-2
13x - 16x = -9
-3x = -9
x = 3
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x+7\right)\)
\(\left(3x+2\right)5x+\left(3x+2\right)1=\left(3x-1\right)5x+\left(3x-1\right)7\)
\(15x^2+10x+3x+2=15x^2-5x+21x-7\)
\(15x^2+13+2=15x^2+16x-7\)
\(15x^2-15x^2-16x+13x+2+7=0\)
\(9-3x=0\)
\(9=3x\)
\(x=3\)
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}=\)\(\frac{3x+2-3x+1}{5x+7-5x+1}\)
\(=\frac{3}{6}=\frac{1}{2}\)
\(\Rightarrow\hept{\begin{cases}3x+2=\frac{5x+7}{2}\\3x-1=\frac{5x+1}{2}\end{cases}}\)\(\Leftrightarrow\)\(\hept{\begin{cases}6x+4=5x+7\\6x-2=5x+1\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=3\\x=3\end{cases}}\)
Vậy x = 3
ĐKXĐ: \(\hept{\begin{cases}5x+7\ne0\\5x+1\ne0\end{cases}}\)=>\(\hept{\begin{cases}x\ne\frac{-7}{5}\\x\ne\frac{-1}{5}\end{cases}}\)
áp dụng tính chất tỉ lệ thức ta có
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}=\frac{\left(3x+2\right)-\left(3x-1\right)}{\left(5x+7\right)-\left(5x+1\right)}=\frac{3}{6}\) \(=\frac{1}{2}\)
=>\(\frac{3x+2}{5x+7}=\frac{1}{2}\)=>2(3x+2)=5x+7 => 6x +4 =5x+7 => x=3 (tm)
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x+7\right)\)
\(5x\left(3x+2\right)+\left(3x+2\right)=5x\left(3x-1\right)+7\left(3x-1\right)\)
\(5x\cdot3x+5x\cdot2+3x+2=5x\cdot3x-5x+7\cdot3x-7\)
\(5x\cdot3x+10x+3x+2=5x\cdot3x-5x+21x-7\)
\(5x\cdot3x+10x+3x-5x\cdot3x+5x-21x=2+7\)
\(-3x=9\)
\(x=9\div\left(-3\right)\)
\(x=-3\)
Chắc sai =))
\(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x+7\right)\)
\(\Leftrightarrow15x^2+13x+2=15x^2+16x-7\)
\(\Leftrightarrow13x+2=16x-7\)
\(\Leftrightarrow2+7=16x-13x\)
\(\Leftrightarrow9=3x\)
\(\Leftrightarrow x=3\)
Chúc bạn học tốt !!!
