If $\alpha ,\beta$ be the zeros of the quadratic polynomial $2-3x-x^2$, then $\alpha +\beta =$

If $\alpha$  and $\beta$ are the zeros of the polynomial then
$\left(x-\alpha \right)\left(x-\beta \right)$ are the factors of the polynomial
Thus, $\left(x-\alpha \right)\left(x-\beta \right)$ is the polynomial.
So, the polynomial $=x^2-\alpha x-\beta x+\alpha \beta$
$=x^2-\left(\alpha +\beta \right)x+\alpha \beta ....(i)$ 
Now,the quadratic polynomial is  
$2-3x-x^2=$ $x^2+3x-2\; ....(ii)$