Question 38365
From
x+y=10 
x*y=20
let us solve for x in the first equation and substitute it into the second equation:
x = 10 - y
then
(10 - y)y = 20
10y - y^2 = 20
now solve
-y^2 + 10y - 20 = 0
y^2 - 10y + 20 = 0
Since this doesn't factor, we can use the quadratic formula:
y = (10 ± sqrt(100 - 80)) / 2
y = (10 ± 2sqrt(5)) / 2
y = 5 ± sqrt(5)
These are your two numbers.