1. 8x^2 + 10x - 9
2. 3x^4 - 14x^2 - 9
3. 4x^2 + 5x - 9
4. 8x^2 + 10x - 18

Answer:
4.
Step-by-step explanation:
(x^2 + 7x - 9) + (3x^2 - 2x) + (x^2 + 7x - 9) + (3x^2 - 2x)
x^2 + 7x - 9 + 3x^2 - 2x + x^2 + 7x - 9 + 3x^2 - 2x
Rearranging order:
3x^2 + 3x^2 + x^2 + x^2 + 7x + 7x - 2x - 2x - 9 - 9
Combine like terms
8x^2 + 10x - 18