Решить системы уравнений : ( 1) x^2=y y-2=2 2) x+y=3 xy=-40 3) x^2+y^2=41 y-x=1 4)x^2-y^2=0 x+y=0 5) x+y-7=0 x^2+xy+y^2=43 ! : (

1) x^2=y            

     y-2=2

x^2=y

y=4

x^2=4

y=4

x1=-2; x2=2

y=4

2) x+y=3

    xy=-40

x=3-y

xy=-40

x=3-y

y^2-3y-40=0

x=3-y

y1=8; y2=-5

x1=-5; x2=8

y1=8; y2=-5

3) x^2+y^2=41

     y-x=1

x^2=y^2=41

y=x+1

x^2+x-40=0

y=x+1

x1=4; x2=-5

y1=5; y2=-4

4) )x^2-y^2=0

   x+y=0

 y=0

x=0

5) x+y-7=0

     x^2+xy+y^2=43

x=7-y

49-14y+y^2+7y-y^2+y^2-43=0

x=7-y

y^2-7y+6=0

x=7-y

y1=6; y2=1

x1=1; x2=6

y1=6; y2=1