已知,x = 2+√3 ,y = √3 -2 ,可得：x+y = 2√3 ,xy = -1 ；x^2+y^2 = (x+y)^2-2xy = 14 ,x^2y^2 = 1 ；x^4+y^4 = (x^2+y^2)^2-2x^2y^2 = 194 ；所以,[(x^4+y^4)÷(x^2+y^2)]∶(x+y) = (194/14)∶(2√3) = (97/42)√...