【正文】
2 ???? acbxaxy 的圖象和性質(zhì) 一、理解新知 直線 abx 2?? ( a bacab 4422?? ,) 頂 ab2? abac442? y 軸 向上 低 ab2?? ab2?? ;向下 高 ab2?? ab2?? 二、知識鞏固練習: (一)選擇: B C D D B B D B (二)填空: 下 x=1 ( 1, 1) 1 90 6 21?x 1 ( 4, 3) 123 yyy ?? 322 ???? xxy ④ (三)解答: 2522125221052542212 ??????????????????????????????xxycbacbacbaab則拋物線的解析式為解得、解:由已知得 8244S03B01A3,1032041D43211D)2(32323121),3,0()3,2(12A B D2122??????????????????????????????????????),(),(即解得得令),(即拋物線的頂點為點則拋物線的解析式為解得則線則拋物線的對稱軸為直、)由已知得、解:(xxxxyyxxxycbcbxCEDD? ),(即解得即得由得由),(即得令解得得令時,當解得上)在拋物線,(點)、解:(32D2,0332303||SS30C,3,0)3()0,1(1,3,0320323)2(3069203A13212A B CA B D21222???????????????????????????????????????? xxxxyyyyyxBxxxxyxxymmmmxxyC?),(得令對稱軸為解得則設),(即得代入令與對稱軸的交點為點最小最小,則最小,則使若使的長度固定而又關于對稱軸對稱、點),(),(軸交于點與拋物線、解:21Q211331303:30C3320BCCQBQCQACACACQCQACQBQABA)2(32)3)(1(03B01A)1(411111112Q A CQ A C22????????????????????????????????????????????????????????yxxxybkbbkbxkylyxxyxxxxxyxcbxxyBC???? xxybabaabaaabxababxxxybxaxyyxxxyCB42422221BAOB C202C222,12,112B21A2112A15222AA2???????????????????????????????????????????解得則),(點角線互相垂直平分可知為菱形時,由菱形的對)當四邊形(),(即則的對稱軸上在拋物線的頂點拋物線),(即,的頂點為拋物線點)、解:(?? 二次函數(shù)