Answer:
Step-by-step explanation:
P(x) + Q(x) = 4x^2 + 6x - 9 -7x^2 - 12x +8
x^2 terms: 4x^2 - 7x^2 = - 3x^2
x terms : +6x - 12x = - 6x
linear term: - 9 + 8 = - 1
Answer: -3x^2 - 6x - 1
