a) \(x^5-x^4-1=\left(x^5-x^4+x^3\right)-\left(x^3+1\right)=x^3\left(x^2-x+1\right)-\left(x+1\right)\left(x^2-x+1\right)=\left(x^2-x+1\right)\left(x^3-x-1\right)\)
b) \(4x^4+y^4=\left[\left(2x^2\right)^2+4x^2y^2+\left(y^2\right)^2\right]-4x^2y^2=\left(2x^2+y^2\right)^2-\left(2xy\right)^2=\left(2x^2-2xy+y^2\right)\left(2x^2+2xy+y^2\right)\)
c) \(4x^4+32x^2+1\)không phân tích được thành nhân tử.
