What two numbers multiply to -15 and add to 2?

Answer 1

xy = -15

x=-15/y

x+ y = 2

-15/y + y = 2

multiply by y

-15 + y^2 = 2y

y^2 -2y -15 = 0

(y-5)(y+3) = 0

y = -3, 5

x = 5 or -3

either (x,y) = (5,-3) or (-3,5)