к5(к+1)-(3+к2)(к4-3к2+9)

k^5(k+1)-(3+k²)(k^4-3k²+9)=

=k^5(k+1)-(k²+3)(k^4-3k²+9)=

=k^5(k+1)-(k^6-3³=

=k^5(k+1)-(k^6-27=

=k^6+k^5-k^6+27=

=k^5+27