【導(dǎo)讀】拋物線y=x2的頂點(diǎn)坐標(biāo)是(),對(duì)稱軸是________,開口向________;物線的開口向上;當(dāng)a________0時(shí),拋物線的開口向下;即當(dāng)x=________時(shí),函數(shù)取得最大值為________;個(gè)單位即可得到拋物線y=-x2+2;把拋物線y=-x2沿y軸向________平移________個(gè)。3.a(chǎn),>,<;x2沿y軸向下平移3個(gè)單位能得到拋物線y=-3x2嗎?