x^2+3xy+y^2+2x+2y=8,
(x+y)^2+2(x+y)+xy=8,
a^2+2a+b=8,①
2x^2+2y^2+3x+3y=14
2(x+y)^2+3(x+y)-4xy=14
2a^2+3a-4b=14②
①*4+②,得,
6a^2+11a=46
6a^2+11a-46=0,
(6a+23)(a-2)=0
所以a=-23/6或a=2,
当a=-23/6时,b=35/36
x+y=-23/36,
xy=35/36
x,y是方程36p^2+23p+35=0的两根,
判别式=△=b^2-4ac