X²+7xy+y²=9
3x-2y=1 2y=3x-1 y=0.5(3x-1)
x²+7x*0.5*(3x-1)+0.25(9x²-6x+1)=9
x²+10.5x-3.5x+2.25x²-1.5x+0.25-9=0
3.25x²+5.5x-8,75=0
13x²+22x-35=0 D=22²+4*13*35=2304 √2304=48
x1=1/26[-22+48]=1
x2=1/26[-22-48]=-35/13
x1=1 y1=0.5(3*1-1)=1
x2=-35/13 y2=0.5(-35*3/13-1)=-105/26-13/26=-59/13