b+2/b=4，∴b^2 - 4b + 2 = 0，∵a^2-4a+2=0，且a≠b∴a、b是x^2 - 4x + 2 = 0的相异实根，a+b = 4，ab = 2∴(a^3 + b^2·a^2 + b^3)/(a-b)^2 = [(a+b)^3 - 3ab(a+b) + (ab)^2]/[(a+b)^2 - 4ab] = [64 - 24 + 4]/[16-8] = 5.5
