已知抛物线y=x2-4x与x轴交于点A，B，顶点为C，则△ABC的面积为______．
人气：261 ℃ 时间：2019-10-19 22:29:22
解答
y=0时，x
2-4x=0
解得x
1=0，x
2=4
∴线段AB的长为4
∵顶点C的纵坐
＝=-4
∴以AB为底的△ABC的高为4
∴S
△ABC=
×4×4=8．
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