What two numbers multiply to - 15 and can also add up to - 7

Let the numbers be x and y

According to the data : xy=-15 and x+y=-7

xy=-15

x+y=-7

y=-7-x

x (-x-7) = - 15

y=-7-x

-x^2-7x=-15

y=-7-x

x^2+7x-15=0

y=-7-x

x = (-7±sqrt (7*7+4*15)) / 2

y=-7-x

x = (-7±sqrt (109)) / 2

Goes to two systems.

1)

y=-7-x

x = (-7+sqrt (109)) / 2

y=-7+3.5-sqrt (109)) / 2

x = (-7+sqrt (109)) / 2

y=-3.5-sqrt (109)) / 2

x = (-7+sqrt (109)) / 2

2)

y=-7-x

x = (-7-sqrt (109)) / 2

y=-7+3.5+sqrt (109)) / 2

x = (-7-sqrt (109)) / 2

y=-3.5+sqrt (109)) / 2

x = (-7-sqrt (109)) / 2