12x(x+3)+5x(x-3)-18(x²- 9)=0
12x²+36x+5x²-15x-18x²+162=
-x²+21x+162=0
x²-21x-162=0
D=441+648=1048
х₁= (21+33)/2=27
х₂= (21-33)/2= -6
x-2y=7
x^2-y^2=24
x=7+2y
x^2+y^2=24
(7+2y)^2-y^2=24
y1=-1
y2= -25\3
подставляем
x=7+2(-1)
x=7+2(-25\3)
x=5
x= -29\3
(x1;y1)=(5;-1)
(x2;y2)=(-29\3;-25\3)