x+y=3
xy=-40
x=3-y
(3-y)*y=-40
3y-y²=-40
y²-3y-40=0
y₁,₂=(3±√(9+160))/2=(3±13)/2
y₁=8, y₂=-5
x₁=-5 x₂=8
{xy=-40
x=3-y
(3-y)y=-40
3y-y²=-40
-y²+3y+40=0
D=(3)²-4(-1)*40=9-(-160)=169=13
x1=(-3-13)/2(-1)=-16/-2=8
x2=(-3+13)/2(-1)=10/-2=-5
y1=3-8 или -40/8
y1=-5
y2=3-(-5) или - 40/-5
y2=8
ответ:x1=8;y1=-5
x2=-5;y2=8
x+y=3
xy=-40
x=3-y
(3-y)*y=-40
3y-y²=-40
y²-3y-40=0
y₁,₂=(3±√(9+160))/2=(3±13)/2
y₁=8, y₂=-5
x₁=-5 x₂=8