a/ đk: x khác -7/5 ; x khác -1/5
pt <=> \(\dfrac{\left(3x+2\right)\left(5x+1\right)}{\left(5x+7\right)\left(5x+1\right)}=\dfrac{\left(3x-1\right)\left(5x+7\right)}{\left(5x+7\right)\left(5x+1\right)}\)
\(\Rightarrow15x^2+13x+2=15x^2+16x-7\)
\(\Leftrightarrow15x^2+13x-15x^2-16x^2=-7-2\)
\(\Leftrightarrow-3x=-9\Leftrightarrow x=3\left(tm\right)\)
vậy x = 3
b/ đk: x khác -1/2; x khác -3
pt <=> \(\dfrac{\left(x+1\right)\left(x+3\right)}{\left(2x+1\right)\left(x+3\right)}=\dfrac{\left(0,5x+2\right)\left(2x+1\right)}{\left(2x+1\right)\left(x+3\right)}\)
\(\Rightarrow x^2+4x+3=x^2+4,5x+2\)
\(\Leftrightarrow x^2+4x-x^2-4,5x=2-3\)
\(\Leftrightarrow-0,5x=-1\Leftrightarrow x=2\left(tm\right)\)
vậy x = 2
a) Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x+1}=\dfrac{\left(3x+2\right)-\left(3x-1\right)}{\left(5x+7\right)-\left(5x+1\right)}=\dfrac{3}{6}=\dfrac{1}{2}\)
\(\Rightarrow2\left(3x+2\right)=5x+7\)
\(\Rightarrow6x+4=5x+7\)
\(\Leftrightarrow x=3\)
Vậy x = 3
b) Ta có: \(\dfrac{0,5x+2}{x+3}=\dfrac{2\left(0,5x+2\right)}{2\left(x+3\right)}=\dfrac{x+4}{2x+6}\)
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{x+1}{2x+1}=\dfrac{0,5x+2}{x+3}=\dfrac{x+4}{2x+6}=\dfrac{\left(x+4\right)-\left(x+1\right)}{\left(2x+6\right)-\left(2x+1\right)}=\dfrac{3}{5}\)
\(\Rightarrow5\left(x+1\right)=3\left(2x+1\right)\)
\(\Rightarrow5x+5=6x+3\)
\(\Leftrightarrow x=2\)
