Question

X+y=-3
X×y=-10
X=?
Y=?

Answer 1

x + y = -3  ⇒ x = -3 - y  

x × y = -10

( - 3 - y ) × y = - 10

-3y - y² = - 10

-y² - 3y + 10 = 0 | × ( -1 )

y² + 3y - 10 = 0

Δ = b² - 4ac = 9 + 40 = 49 = 7²

y₁,₂ = ( -b ± √Δ ) / 2a

y₁ = ( -3 + 7 ) / 2 = 4 / 2 = 2

y₂ = ( -3 - 7 ) / 2 = -10 / 2 = -5

y₁ = 2 ⇒ x₁ + 2 = -3 ⇒ x₁ = -3 - 2 = -5  

y₂ = -5 ⇒ x₂ - 5 = -3 ⇒ x₂ = -3 + 5 = 2

x₁ = -5, y₁ = 2

x₂ = 2, y₂ = -5