\(\frac{\left(3x+1\right)\left(3x-2\right)}{3}+5\left(3x+1\right)=\frac{2\left(2x+1\right)\left(3x+1\right)}{3}+2\left(3x+1\right)\)
\(\Leftrightarrow\frac{2\left(2x+1\right)\left(3x+1\right)-\left(3x+1\right)\left(3x-2\right)}{3}-3\left(3x+1\right)=0\)
\(\Leftrightarrow\frac{\left(4x+2\right)\left(3x+1\right)-\left(3x+1\right)\left(3x-2\right)}{3}-3\left(3x+1\right)=0\)
\(\Leftrightarrow\frac{12x^2+10x+2-9x^2+6x-3x+2}{3}-9x-3=0\)
\(\Leftrightarrow\frac{3x^2+13x+4-27x-9}{3}=0\Leftrightarrow\frac{3x^2-14x-5}{3}=0\)
\(\Leftrightarrow3x^2-14x-5=0\Leftrightarrow3x^2-14x=5\Leftrightarrow x\left(3x-14\right)=5\)
\(.................\)
v: Làm tiếp nè
3x^2 - 14x - 5 = 0
<=> 3x^2 - 15x + x - 5 = 0
<=> ....
