(a-b)²/8a -[(a+b)/2 -√ab]
=(√a +√b)²(√a -√b)²/8a -4a(√a -√b)²/8a
=(√a -√b)²[(√a +√b)²-4a]/8a .(1)
∵a>b>0,
∴√a +√b (√a +√b)²[(√a +√b)²-4a](1)(a-b)²/8a