Question

．(6分)已知二次函數(shù)的圖象與y軸交于點(diǎn)A(0，－6)，與x軸的一個(gè)交點(diǎn)坐標(biāo)是B(－2，0)．

(1)求二次函數(shù)的關(guān)系式，并寫出頂點(diǎn)坐標(biāo)；

(2)將二次函數(shù)圖象沿x軸向左平移個(gè)單位長(zhǎng)度，求所得圖象對(duì)應(yīng)的函數(shù)關(guān)系式．

 

 

Answer 1

解：（1）把A(O，-6)代入y=x²+bx+c求得 ···························································（1分）

把B(-2，0)代入y=x²+bx-6求得 ··························································（2分）

所以················································································（3分）

所以頂點(diǎn)坐標(biāo) ····························································································（4分）

(2)二次函數(shù)圖象沿x軸向左平移個(gè)單位長(zhǎng)度得： ··············（6分）

 

解析:略