x²=(2-根号2)²=4-4根号2+2=6-4根号2
y²=(2+根号3)²=4+4根号3+2=6+4根号2
xy=(2-根号3)(2+根号3)=2²-(根号2)²=2
X方+XY+Y方=6-4根号2+2+6+4根号2=14