Given x2 + X + 1 = 0, find X4 + 1 / X4
x²+1=-x
Square on both sides
x⁴+2x²+1=x²
x⁴+1=-x²
Square on both sides
x^8+2x⁴+1=x⁴
x^8+1=-x⁴
Divide both sides by X & # 8308;
x⁴+1/x⁴=-1
Decomposition factor: x4-x3 + 4x2 + 3x + 5
x4-x3+4x2+3x+5=(x4+x3+x2)-(2x3+2x2+2x)+(5x2+5x+5)=x2(x2+x+1)-2x(x2+x+1)+5(x2+x+1)=(x2-2x+5)(x2+x+1).
Decomposition factor: x4-4x2 + 3 =?
Original = (X & # 178; - 1) (X & # 178; - 3)
=(x+1)(x-1)(x²-3)