Question

what multiplies to -18 and adds to -1

Answer 1

xy=-18
x+y=-1

so subtract y both sides 2nd eq
x+y-y=-1-y
x=-1-y

we now know what x is plug it in first eq

(-1-y)y = -18
-y +y^2= -18 now add 18 to both sides
y^2 - y +18 = 0

this can not be factored
use quadratic equation
the calculator gives imaginary numbers

Answer 2

Careful,

(-1-y)y = -18
-y -y^2= -18 now add 18 to both sides
-y^2 - y +18 = 0
y^2 + y - 18 = 0

with this quadratic equation
there are two (real, but irrational) soultions

Answer 3

thanks UnkleRhaukus