Solve x^9-x^5+x^4-1=0 and x^11-x^7+x^4-1=0 | De-Moivre's theorem |nthe root of unity | IIT JEE

Solve the following equations
x^9-x^5+x^4-1=0
x^11-x^7+x^4-1=0
nth root of unity concept. In these equations we also solve the 4th root of unity, 5th root of unity, 7th root of unity
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