a, $2x^3 + 5x^2 -3x=0$
$⇔x(2x^2+5x-3)=0$
$⇔x(x+3)(2x+1)=0$
$⇔x=0;x=-3;x=-1/2$
Vậy S={0;-3;-1/2}
b, $2x^3 + 6x^2 =x^2 +3x$
$⇔2x(x^2+3x)-(x^2+3x)=0$
$⇔(x^2+3x)(2x-1)=0$
$⇔x(x+3)(2x-1)=0$
$⇔x=0;x=-3;x=1/2$
Vậy S+{0;-3;1/2}
c, $x^2 +(x +2)(11x - 7)=4$
$⇔x^2+(x+2)(11x-7)-4=0$
$⇔(x-2)(x+2)+(x+2)(11x-7)=0$
$⇔(x+2)(x-2+11x-7)=0$
$⇔(x+2)(12x-9)=0$
$⇔x=-2;x=3/4$
Vậy S+{-2;3/4}
d, $( x - 1)(x^2 + 5x - 2) - (x^3 - 1)=0$
$⇔(x-1)(x^2+5x-2)-(x-1)(x^2+x+1)=0$
$⇔(x-1)(x^2+5x-2-x^2-x-1)=0$
$⇔(x-1)(4x-2)=0$
$⇔x=1;x=1/2$
Vậy S={1;1/2}
e, $x^3 + 1=x(x +1)$
$⇔(x+1)(x^2-x+1)-x(x+1)=0$
$⇔(x+1)(x^2-x+1-x)=0$
$⇔(x+1)(x-1)^2=0$
$⇔x=-1;x=1$
Vậy S={±1}
f, $x^3 + x^2 + x + 1=0$
$⇔(x+1)(x^2+1)=0$
$⇔x=-1$
Vậy S={-1}
g, $x^3 - 3x^2 + 3x - 1=0$
$⇔(x-1)(x^2-2x+1)=0$
$⇔(x-1)(x-1)^2=0$
$⇔x=1$
Vậy S={1}
h, $x^3 - 7x +6=0$
$⇔(x-1)(x^2-6)=0$
$⇔x=1;x=±√6$
Vậy S={1;±√6}
i, $ x^6 - x^2=0$
$⇔x^2(x^5-1)=0$
$⇔x=0;x=1$
Vậy S={0;1}
j, $x^3 - 12=13x$
$⇔x²-12-13x=0$
$⇔(x+1)(x-12)=0$
$⇔x=-1;x=12$
Vậy S={-1;12}
l, $x^3=4x$
$⇔x(x-2)(x+2)=0$
$⇔x=0;x=±2$
Vậy S={0;±2}
m, $1/9(x - 3)^2 - 1/25(x + 5)=0$
$⇔(1/3x-3)^2-(1/5x+5)^2=0$
$⇔(x/3-3-x/5-5)(x/3-3+x/5+5)=0$
$⇔(2x/15-8)(8x/15+2)=0$
$⇔x=60;x=-15/4$
Vậy S={60;-15/4}
n, $(3x/5 - 1/3)^2=(x/5 + 2/3)^2$
$⇔(3x/5-1/3-x/5-2/3)(3x/5-1/3+x/5+2/3)=0$
$⇔(2x/5-1)(4x/5+1/3)=0$
$⇔x=5/2;x=5/12$
Vậy S={5/2;5/12}
