知识与财富的链接
§１． ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｅｓｔｕｄｙｏｆｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓａｎｄｏｔｈｅｒｍａｔｈｅｍａｔｉｃａｌｆｉｅｌｄｓ，ｏｎｅｕｓｕａｌｌｙｎｅｅｄｔｏｄｅａｌｗｉｔｈｔｈｅｐｏｓｉｔｉｖｅｄｅｆｉｎｉｔｅ，ｎｅｇａｔｉｖｅｄｅｆｉｎｉｔｅｐｒｏｂｌｅｍｓｏｆｂｉｎａｒｙｑｕａｒｔｉｃｆｏｒｍｓ，ｓｅｅ［１，２］．Ｉｔｉｓｗｅｌｌ－ｋｎｏｗｔｈａｔｉｎｔｈｅｃａｓｅｏｆｑｕａｄｒａｔｉｃｆｏｒｍ，ｔｈｅｒｅｅｘｉｓｔｍａｎｙｃｒｉｔｅｒｉｏｎｓｆｏｒｔｈｅｐｏｓｉ…
In this paper,we discussed the positive definite problem of binary quartic forms and obtained a necessary and sufficient conditions.
