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
數(shù)學(xué)活動(dòng)一,(1)在一張紙上作出函數(shù)y=x²2x+3的圖象.,(1)在一張紙上作出函數(shù)y=x²2x+3的圖象.,解:列表,計(jì)算:,(1)在一張紙上作出函數(shù)y=x²2x+3的圖象.,解:列表,計(jì)算:,(1)在一張紙上作出函數(shù)y=x²2x+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=x²2x+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,AA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(lái)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?,