1.å¦æx-yæ¯æ ¹å·éé¢çï¼é£ä¹x-yâ¥0ï¼å³xâ¥y
å®ä¹åå°±æ¯{(x,y)|xâ¥y}
å¦æxææ¯æ ¹å·éé¢çï¼é£ä¹xâ¥0
å®ä¹åå°±æ¯{(x,y)|xâ¥0}
2.çæ¯æ°åæ±å
1+1/3+1/9+1/27+...+1/3^n
=1*[1-(1/3)^(n+1)]/(1-1/3)
=3*[1-(1/3)^(n+1)]/2
3.è¿ä¸ªè¦ç¨å°å®ç§¯åçç¥è¯
é¢ç§¯ä¸ºS=â«(x-1)^2dx(ä¸éæ¯1ï¼ä¸éæ¯0)
=â«(x^2-2x+1)dx(ä¸éæ¯1ï¼ä¸éæ¯0)
=[x^3/3-x^2+x]|(ä¸éæ¯1ï¼ä¸éæ¯0)
=[1^3/3-1^2+1]-[0^3/3-0^2+0]
=1/3
温馨提示:答案为网友推荐,仅供参考