图象经过点A(1,0)B(x2,0),代入
a-4a+c=0,c=3a
a(x2)^2-4ax2+c=0
a(x2)^2-4ax2+3a=0
(ax2-3a)(x2-1)=0
x2=3或x2=1(与A重合,舍)
与y轴正半轴交于点C,
令x=0,y=c>0
所以点C(0,c)
S△ABC=2
1/2 *AB*c=2,AB=|x2-1|=2
即c=2,a=c/3=2/3
二次函数y=ax^2-4ax+c=2/3 x^2 -8/3 x +2
图象经过点A(1,0)B(x2,0),代入
a-4a+c=0,c=3a
a(x2)^2-4ax2+c=0
a(x2)^2-4ax2+3a=0
(ax2-3a)(x2-1)=0
x2=3或x2=1(与A重合,舍)
与y轴正半轴交于点C,
令x=0,y=c>0
所以点C(0,c)
S△ABC=2
1/2 *AB*c=2,AB=|x2-1|=2
即c=2,a=c/3=2/3
二次函数y=ax^2-4ax+c=2/3 x^2 -8/3 x +2