x^7+x^5+1=(x^7+x^6+x^5)+(1-x^6)=x^5(x^2+x+1)+(1+x^3)(1-x)(1+x+x^2)=(x^2+x+1)(x^5-x^4+x^3-x+1)
x^7+x^5+1=(x^7+x^6+x^5)+(1-x^6)=x^5(x²+x+1)+(1+x³)(1-x)(1+x+x²)=(x²+x+1)(x^5-x^4+x³-x+1)
