a) x²- x = 0
x(x - 1) = 0
x = 0 или x - 1 = 0
x = 0 или x = 1
б) $$ \frac{x+3}{4} - \frac{x}{2} = 3 $$
$$ \frac{x+3}{4} - \frac{2x}{4} = \frac{12}{4} $$
$$ x + 3 - 2x = 12 $$
$$ -x = 9 $$
$$ x = -9 $$
Ответ: а) 0, 1; б) -9