九年級(jí)數(shù)學(xué)下冊(cè) 第26章 數(shù)學(xué)活動(dòng)課件1 新人教版.ppt

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數(shù)學(xué)活動(dòng)一,(1)在一張紙上作出函數(shù)y=x2－2x+3的圖象.,(1)在一張紙上作出函數(shù)y=x2－2x+3的圖象.,解：列表，計(jì)算：,(1)在一張紙上作出函數(shù)y=x2－2x+3的圖象.,解：列表，計(jì)算：,(1)在一張紙上作出函數(shù)y=x2－2x+3的圖象.,解:1.列表，計(jì)算：,2.描點(diǎn)，畫圖：,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,描點(diǎn) 畫圖,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,,,,,,,,,,x,y,O,,,,,,向后翻折,(2)沿x 軸把這張紙向后折疊,沿著x軸,,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,,,,,,,,,,x,y,O,,,描出拋物線y=x2-2x+3 關(guān)于x軸對(duì)稱的拋物線,在后面的紙上留下痕跡,再次描拋物線,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,,,,,,x,y,O,,,,,向前展開,,,把折到后邊的紙向前展開,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,描出拋物線 y=x2－2x+3 關(guān)于x軸對(duì)稱 的拋物線,按紙上的痕跡描出圖象,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,這條拋物線的解析式是什么？,（3）請(qǐng)寫出新描出的拋物線的解析式,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,,A,A’,對(duì)稱點(diǎn)A’點(diǎn)與A點(diǎn)的坐標(biāo)有什么關(guān)系？,分析：,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,,A,A’,,A’A到x軸的距離相等 縱坐標(biāo)互為相反數(shù) 即：,,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,,A,A’,,,,所求的新函數(shù)為:,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,這條拋物線的解析式是什么？,還有其他方法來求么？,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,你只要知道它上面的幾個(gè)點(diǎn)就可以求出解析式？,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,,,知道哪些條件可確定解析式？,,,-5,,,,,,,,,,5,,,,6,,,4,,,2,,,,-2,,,-4,,,-6,,,-8,,,,,,,,,,,,x,y,O,,,如果把y=x2-2x+3,(1)沿其他直線對(duì)折；,(2)進(jìn)行平移后，,你能否求出解析式?,