Two numbers multiply to make -9 and add to make -4, what are the numbers?

a+b =- 4       so    a = - 4-b

 

ab = -9       sub in for a

 

(-4-b)b = -9

-4b-b^2+9 = 0

 

-b^2-4b+9 = 0           Quadratic Formula   shows     and b =  −5.60555   1.60555          or    -2 +-sqrt13