Answer:

11+a²

Step-by-step explanation:

#cary on learning

Answer:

=(3x³ + x² - 1) + 3(-x³ + x² + 5)​

=(3x^5 - 1) + 3(x + 5)​

=3x^5 - 1+ 3x +15

=3x^5+ 3x +15-1

=3x^5+ 3x +14