$a)3x^2+6x=0$

$3x\left(x+2\right)=0\mid :3$

$x\left(x+2\right)=0$

$x=0lubx+2=0$

$x=-2$

$x\in \left\{0,2\right\}$

 

$b)7x-3x^2=0$

$x\left(7-3x\right)=0$

$x=0lub7-3x=0$

$7=3x\mid :3$

$x=\frac{7}{3}=2\frac{1}{3}$

$x\in \left\{0,2\frac{1}{3}\right\}$

 

 

 

$c)2x^2=5x\mid -5x$

$2x^2-5x=0$

$x\left(2x-5\right)=0$

$x=0lub2x-5=0\mid +5$

$2x=5\mid :2$

$x=\frac{5}{2}=2\frac{1}{2}$

$x\in \left\{0,2\frac{1}{2}\right\}$

 

 

 

$d)8x=\frac{1}{2}{x}^2\mid -8x$

$\frac{1}{2}{x}^2-8x=0\mid \cdot 2$

$x^2-16x=0$

$x\left(x-16\right)=0$

$x=0lubx-16=0$

$x=16$

$x\in \left\{0,16\right\}$