Câu 2$a)x^3-16x=0$
$->x(x^2-16)=0$
$-> x(x^2-4^2)=0$
$-> x(x-2)(x+2)=0$
Nếu $x=0-> x=0$
hoặc $x-2=0-> x=2$
hoặc $ x+2=0-> x=-2$
$b)2x^3-x^2+2-1=0$
->$ (2x^3-x^2)+(2x-1)$
->$x^2(2x-1)+(2x-1)=0$
->$(2x-1)(x^2+1)=0$
Nếu $2x-1=0-> x=1/2$
hoặc $x^2+1=0->$ vô nghiệm
Câu 3:
$a) x^2 +x-2xy-2y$
=$(x^2-2xy)+(x-2y)$
=$x(x-2y)+(x-2y)$
=$(x-2y)(x+1)$
$b)x^2-5x+6$
=$x^2-2x-3x+6$
=$(x^2-2x)-(3x-6)$
=$x(x-2)-3(x-2)$
=$(x-2)(x-3)$
$c)x^3-y^3+2x^2+2xy$
$d) x^5+x+1$
$x^5-x^4+x^4-x^3+x^3-x^2+x^2+x+1$
=$(x^5+x^4+x^3)-(x^4+x^3+x^2)+(x^2+x+1)$
=$x^3(x^2+x+1)-x^2(x^2+x+1)+(x^2+x+1)$
=$ (x^2+x+1)(x^3-x^2+1)$
=$(x^2+x+1)$
$#Hoctot$
$@vohaiy2806$
