What two numbers multiply to 8 and add to -6?

Let the numbers be 'm' & 'n'

Hence

mn = 8

m + n = -6

m = 8/n

Substitute

8/n + n = -6

Multiply through by 'n'

8 + n^(2) = -6n

n^(2) + 6n + 8 = 0

Factor

(n + 4 )(n + 2) = 0

Hence n = -4 & n = -2