Which polynomial is equal to (4x^2+3x-1) + (-3x^2-5x-8) ?

In adding two polynomials, you have to remember that you can only add like terms. Like terms are terms that the same variable and exponent.

The expression would become like this:

4x^2 + 3x - 1 + - 3x^2 - 5x - 8

Now, you should add the like terms:

x^2 - 2x - 9