Question

What numbers add up to -9 but multiply to 8?

Answer 1

-8 & -1

Explanation:

Let the numbers be x and y

x+y = -9 (1)

xy = 8 (2)

(1) x = -9-y

(2) (-9-y)y = 8

-9y-y² = 8

y²+9y+8 = 0

y²+8y+y+8 = 0

y(y+8)+1(y+8) = 0

(y+8)(y+1) = 0

y = -8 , -1

x = -9-y

If y = -8, x = -9-(-8) = -1

If y = -1, x = -9-(-1) = -8

Either ways, the numbers are -8 & -1

Answer 2

The numbers -8 and -1 can do that.