因式分解x8+x7+18,7为X的次数
1个回答

X^8+X^7+1

=X^8+X^7+X^6-X^6+1

=X^6(X^2+X+1)-(X^6-1)

=X^6(X^2+X+1)-(X^3+1)(X^3-1)

=X^6(X^2+X+1)-(X^3+1)(X-1)(X^2+X+1)

=(X^2+X+1)[X^6-(X^3+1)(X-1)]

=(X^2+X+1)(X^6-X^4+X^3-X+1)