Question

x²(x²+4)-x²-4=0

Answer 1

\(\Leftrightarrow\left(x^2+4\right)\left(x^2-1\right)=0\)

=>x=1 hoặc x=-1

Answer 2

<=> \(x^2\left(x^2+4\right)-\left(x^2+4\right)=0\)

<=> \(\left(x^2+4\right)\left(x^2-1\right)=0\)

<=> \(\left(x^2+4\right)\left(x-1\right)\left(x+1\right)=0\)

<=> x = 1 và x = - 1 vì x² + 4 luôn luôn lớn hơn 0.

Answer 3

\(x^2\left(x^2+4\right)-x^2-4=0\\ < =>x^2\left(x^2+4\right)-\left(x^2+4\right)=0\\ < =>\left(x^2+4\right)\left(x^2-1\right)=0\)

\(Vì :x^2\ge 0=>x^2+4\ge4>0\)

\(=>x^2-1=0\\ < =>x^2=1\\ < =>x=\pm1\)

\(Vậy :\) \(S=\left\{\pm1\right\}\)