Question

Cum se rezolva sistemul :
$\left \{ {{x+y=-6} \atop {xy=8}} \right.$

Answer 1

x+y=-6
x=-6-y
xy=8
y(-6-y)=8
-6y-y²=8
-y²-6y-8=0
y²+6y+8=0
Δ=36-32=4
√Δ=2
y₁=-4
y₂=-2
x₁=-6+4=-2
x₂=-6+2=-4

avem sol   x₁=-2  si y₁=-4
                  x₂=-4  si y₂=-2