Answer:3x² - 2x + 5.
Explanation:
I can help you with that. To add two polynomials, you need to combine the like terms. Like terms are terms that have the same variable and exponent. For example, 5x² and 8x² are like terms, but 5x² and x are not. So, to add (-5x²-3x + 9) + (8x²+x-4), you need to do the following:
Combine the like terms of x²: -5x² + 8x² = 3x²
Combine the like terms of x: -3x + x = -2x
Combine the constant terms: 9 - 4 = 5
The final answer is 3x² - 2x + 5.