Решите систему: 9х^2+9y^2=13 3хy=2 ,

9x^2+9y^2=13     9x^2+9y^2=13        9(4/9y^2)+9y^2=13    4/y^2+9y^2=13

3xy=2                   x=2/3y                   x=2/3y                      x=2/3y

4+9y^4=13y^2      y^2 назначим на z   9z^2-13z+4=0

x=2/3y                                                D=25

z1=13+5/18=1

z2=13-5/18=4/9

(y1)^2=1      (y2)^2=4/9     x1=2/3(y1)    x2=2/3(y2)

y1=1             y3=2/3           x1=2/3         x3=1

y2=-1            y4=-2/3          x2=-2/3        x4=-1

ответ:{(2/3;1);(-2/3;-1);(1;2/3);(-1;-2/3)}