如图1，已知直线y=x+3与x轴交于点A，与y轴交于点B，抛物线y=-x2+bx+c经过A、B两点，与x轴交于另一个点C， 已知：如图，直线y=-x+3与x轴、y轴分别交于B、C，抛物...
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（1）∵y=x+3与x轴交于点A，与y轴交于点B，∴当y=0时，x=-3，即A点坐标为（-3，0），
当x=0时，y=3，即B点坐标为（0，3），
将A（-3，0），B（0，3）代入y=-x2+bx+c，
得
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