Question

Помогите решить
{x-5y=9
{x^2+3xy-y^2=3

Answer 1

x=9+5y
(9+5y)²+3y(9+5y)-y²-3=0
81+90y+25y²+27y+15y²-y²-3=0
39y²+117y+78=0
y²+3y+2=0
y1+y2=-3 U y1*y2=2
y1=-2⇒x1=9-10=-1
y2=-1⇒x2=9-5=4
(-1;-2) U (4;-1)