x²＋y²/2=1则：2x²＋y²=2则：x√(1＋y²)=(√2/2)×√[(2x²)(1＋y²)]而：√[(2x²)(1＋y²)]≤[(2x²)＋(1＋y²)]/2=(1＋2x²＋y²)/2=3/2则：x√(1＋y&...