\(\left(x^4+2x^2+1\right)+2.\dfrac{x}{2}\left(x^2+1\right)+\dfrac{x^2}{4}-\dfrac{25}{4}x^2=0\\ \Rightarrow\left(x^2+1\right)^2+2.\dfrac{x}{2}\left(x^2+1\right)+\left(\dfrac{x}{2}\right)^2-\left(\dfrac{5}{2}x\right)^2=0\\ \Rightarrow\left(x^2+1+\dfrac{x}{2}\right)^2-\left(\dfrac{5}{2}x\right)^2=0\\ \Rightarrow\left(x^2-2x+1\right)\left(x^2+3x+1\right)=0\)
Tự giải típ :V