Question

x^2+y^2=4
x-y=2

x+y=7
xy=12​

Answer 1

Объяснение:

1.x^2+y^2=4

x=2+y

(2+y)^2+y^2=4

4+4y+y^2+y^2=4

2y^2+4y+4=4

2y^2+4y=0 /2

y^2+2y=0

y(y+2)=0

y1=0 y+2=0

y2=-2

x1=2+0=2

x2=2-2=0

----------------

x+y=7

xy=12

x=7-y

(7-y)y=12

7y-y^2=12 /-1

y^2-7y+12=0

D= 49-4*1*12=1

y1=3

y2=4

x1=7-3=4

x2=7-4=3