xy = -900
x + y = 5
x + y = 5
x - x + y = -x + 5
y = -x + 5
xy = -900
x(-x + 5) = -900
x(-x) + x(5) = -900
-x² + 5x = -900
-x² + 5x + 900 = 0
-1(x²) - 1(-5x) - 1(-900) = 0
-1(x² - 5x - 900) = 0
-1 -1
x² - 5x - 900 = 0
x = -(-5) ± √((-5)² - 4(1)(-900))
2(1)
x = 5 ± √(25 + 3600)
2
x = 5 ± √(3625)
2
x = 5 ± 5√(145)
2
x = 2.5 ± 2.5√(145)
x + y = 5
2.5 ± 2.5 √(145) + y = 5
- (2.5 ± 2.5√(145) - (2.5 ± 2.5√(145)
y = 2.5 ± 2.5√(145)
(x, y) = (2.5 ± 2.5√(145), 2.5 ± 2.5√(145))
The two numbers that add up to 5 and multiply to -900 are 2.5 ± 2.5√(145).
