∵a-b和√a-√b同号即(a-b)(√a-√b)≥0∴a√a - b√a + b√b - a√b≥0a√a + b√b≥a√b + b√a两边同时除以√(ab),得a/√b + b/√a≥√a + √b
a/√b+√b>=2√[(a/√b)*(√b)]=2√ab/√a+√a>=2√[(b/√a)*(√a)]=2√b 相加a/√b+√b+b/√a+√a>=2√a+2√ba/√b+b/√a>=√a+√b