a) x5+x+1=(−x4−x3+x+1)+(x5+x4+x3)=−x3(x+1)+(x+1)+x3(x2+x+1)
=(1−x3)(x+1)+x3(x2+x+1)=(1−x2)(x2+x+1)+x3(x2+x+1)
=(x3−x2+1)(x2+x+1)
b)x7+x2+1=x7−x4+x4−x+x2+x+1=x4(x3−1)+x(x3−1)+(x2+x+1)
=(x4+x)(x3−1)+(x2+x+1)=(x4+x)(x−1)(x2+x+1)+(x2+x+1)
=(x2+x+1)(x5−x4+x2−x+1)
Vote nếu thấy có ích ( ͡° ͜ʖ ͡°)