a) 23x(x2−4)=0
⇔23x(x2−22)=0
⇔23x(x−2)(x+2)=0
⇔ Hoặc x=0
Hoặc x–2=0⇒x=2
Hoặc x+2=0⇒x=−2
Vậy x=0,x=−2,x=2
b) (x+2)2−(x−2)(x+2)=0
⇔(x+2)[(x+2)−(x−2)]=0
⇔(x+2)(x+2−x+2)=0
⇔(x+2).4=0
⇔x+2=0
⇔x=−2
Vậy x=−2
c) x+2√2x2+2x3=0
⇔x(1+2√2x+2x2)=0
⇔x(12+2√2x.1+(√2x)2)=0
⇔x(1+√2x)2=0
⇔ Hoặc x=0
Hoặc (1+√2x)2=0⇒1+√2x=0⇒x=−1√2
Vậy x=0,x=−1√2