{y²+xy=12
{3y-x=10
х=(3у-10)
у²+у(3у-10)=12
у²+3у²-10у-12=0
4у²-10у-12=0
D=(-(-10))²-4×4×(-12)=100+192=292
y1=(-(-10)-√292)/2×4=(10-17,088)/8=-7,088/8=-0,886
y2=(-(-10)+√292)/2×4=(10+17,088)/8=27,088/8=3,386
x1=3y1-10
x1=3×(-0,886)-10
x1=-2,658-10
x1=-12,658
x2=3y2-10
x2=3×3,386-10
x2=10,158-10
x2=0,158
(-12,658;-0,886); (0,158;3,386).