a) $(3x-1)(x+3)=(2-x)(5-3x)$
$⇔3x^2+8x-3=10+3x^2-11x$
$⇔19x = 13 $
$⇔x=13/19$
b) $(x+2)(2x-3)-3(x-2)=2(x-1)^2$
$⇔2x^2+x-6+6-3x=2x^2-4x+2$
$⇔2x=2 $
$⇔x=1$
c) $(x+2)-(3x+6)=0$
$⇔-2x-4=0$
$⇔x=-2$
d) $(3x+5)(2x+1)=(6x-2)(x-3)$
$⇔6x^2+13x+5=6x^2-20x +6$
$⇔33x = 1 $
$⇔x=1/33$
e) $(x+1)^2-x(x-2)=0$
$⇔x^2+2x+1-x^2+2x=0$
$⇔x=\dfrac{-1}{4}$
f) $x(x-6)=(x-3)^2-9$
$⇔x^2-6x=x^2-6x $ ( Luôn đúng )
g) $(x-1)(x^2+x+1)=x(2x^2+1)-x^3$
$⇔x^3-1=2x^3+x-x^3$
$⇔x=-1$
h)$(x-6)^2=(x-5)(x-7)$
$⇔x^2-12x+36=x^2-12x+35 $
$⇔1=0 $ ( Vô lí )