Answer:
-1 and 21
Step-by-step explanation:
Let the numbers be x and y.
x + y = 20
xy = -21
Solve the first equation for x and substitute in the second equation.
x = 20 - y
(20 - y)y = -21
20y - y^2 = -21
y^2 - 20y - 21 = 0
(y - 21)(y + 1) = 0
y - 21 = 0 or y + 1 = 0
y = 21 or y = -1
For y = 21:
x = 20 - y
x = 20 - 21
x = -1
For y = -1:
x = 20 - y
x = 20 - (-1)
x = 21
Solutions: (-1, 21) and (21, -1)
Answer: the numbers are -1 and 21
