证：由于 （a/√b + b/√a) - (√a + √b) == (b-a)/√a - (b-a)/√b == (b - a)(1/√a - 1/√b);(1) 若a>b,则b - a 0,故(b - a)(1/√a - 1/√b)>0,原式得证.(3)当且仅当a == b时,有(b - a)(1/√a - 1/√b) == 0；综...