Choose the missing exponent to create a polynomial: 3x^4+4x^2-9x^-? +2
1)2
2)3
3)-9
4)7
5)4

The polinomials only can have positive whole exponents, that is: 1, 2, 3, 4, 5, 6, ... (you can include 0 also, because it iis the independent term).

So, if you are told that one term of the polynomial is 9 x ^ (negative something), it is necessary that the number after the negative sign be negative, given that negative times negative is positive.

Therefore, the only possible option from the answer choices is the option 3) -9.

3) - 9