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

-8 & -1

Step-by-step 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

a mantle plume is an upwelling of abnormally hot rock within the earth's mantle. as the heads of mantle plumes can partly melt when they reach shallow depths, they are thought to be the cause of volcanic centers known as hotspots and probably also to have caused flood basalts.

step-by-step explanation: