Question

抛物线y=a(X+h)²+K经过点(-1,-4),且当X=1时,Y有最值是-2,求该抛物线的解析式.

Answer 1

代入方程

-4=a﹙-1+h）²+k ①

-2=a(1+h)²+k ②

①-②

-2=a(-1+h)²-a(1+h)²=a(-1+h-1-h)(-1+h+1+h)=-4ah

ah=1/2

x=1,y最值,

∴h=-1

a=-1/2

k=-2

y=-1/2(x-1)²-2