y=0.5(x-1)(x-2)
y=-0.5(x-1)(x-2)
y=0.5(x+1)(x+2)
y=-0.5(x+1)(x+2)
y=0.5(x-1)(x+2)
y=-0.5(x-1)(x+2)
y=0.5(x+1)(x-2)
y=-0.5(x+1)(x-2)
x=0,与y轴交于C
y=ax²+bx+c=0+c,c=1,
y=0,与x轴交于A,OA=2,
0=ax²+bx+c=a(2²)+2b+1,4a+2b+1=0,...(1)
y=0,与x轴交于B,OB=1,
0=ax²+bx+c=a(1²)+b+1,a+b+1=0,...(2),
解方程组(1),(2):得a=1/2,b=-3/2,函数的解析式
y=ax²+bx+c=x²/2-3x/2+1