（1）：5x^4+3x^2-10-3x^2y+x^4-1
=5x^4+x^4+3x^2-3x^2y-10-1
=6x^4+3x^2-3x^2y-11


(2):p^2+3pq+6-8p^2+pq
=p^2-8p^2+3pq+pq+6
=-7P^2+4pq+6