1) {x^2-y=4; {x^2-y=4; (2y-7)^2-y=4;
{2y-x=7; {x=2y-7;
4y^2-28y+49-y=4; 4y^2-27y+49-4=0; 4y^2-27y+45=0; D=9; y1=3; y2=3.75.
x1= -1; x2=0.5/
2) {x^2+y^2=5; {x^2+y^2=5;
{x-y=1; {x=y+1;
(y+1)^2 + y^2 -5=0; y^2+2y+1+y^2-5=0; 2y^2+2y-4=0; y^2+y-2=0; D=9; y1=1; y2=-2.
x1=2; x2=-1