a = 1/(3+2根号2) = (3-2根号2) / (9-8) = 3-2根号2
b = 1/(3-2根号2) = 3+2根号2
a+b = 6
2根号ab = 2根号(9-8) = 2
a-b = -4根号2
a-b除以a-2根号ab+b = (-4根号2) / (6-2) = -根号2.