x=(2+根号3)/(2-根号3)=(2+根号3)^2
y=(2-根号3)/(2+根号3)=(2-根号3)^2
x-y = (2+根号3)^2 - (2-根号3)^2 = 8根号3
x×y = (2+根号3)^2 × (2-根号3)^2 = {(2+根号3) (2-根号3)}^2 = 1^2 = 1
2x的平方-3xy+2y平方
= 2x的平方-4xy+2y平方 +xy
= 2(x-y)^2+xy
= 2×(8根号3)^2 + 1
= 384+1
= 385