已知:抛物线y=x²-2x-8 (1)求抛物线与坐标轴交点A,B,C的坐标 (2)若抛物线顶点为D,与X轴交点A,B,求△ABC的面积
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/27 14:10:20
![已知:抛物线y=x²-2x-8 (1)求抛物线与坐标轴交点A,B,C的坐标 (2)若抛物线顶点为D,与X轴交点A,B,求△ABC的面积](/uploads/image/z/11948281-25-1.jpg?t=%E5%B7%B2%E7%9F%A5%3A%E6%8A%9B%E7%89%A9%E7%BA%BFy%3Dx%26%23178%3B-2x-8+++++++++++++++++++++++++++++++++++++++++++++++++++++++++%EF%BC%881%EF%BC%89%E6%B1%82%E6%8A%9B%E7%89%A9%E7%BA%BF%E4%B8%8E%E5%9D%90%E6%A0%87%E8%BD%B4%E4%BA%A4%E7%82%B9A%2CB%2CC%E7%9A%84%E5%9D%90%E6%A0%87+%EF%BC%882%EF%BC%89%E8%8B%A5%E6%8A%9B%E7%89%A9%E7%BA%BF%E9%A1%B6%E7%82%B9%E4%B8%BAD%2C%E4%B8%8EX%E8%BD%B4%E4%BA%A4%E7%82%B9A%2CB%2C%E6%B1%82%E2%96%B3ABC%E7%9A%84%E9%9D%A2%E7%A7%AF)
已知:抛物线y=x²-2x-8 (1)求抛物线与坐标轴交点A,B,C的坐标 (2)若抛物线顶点为D,与X轴交点A,B,求△ABC的面积
已知:抛物线y=x²-2x-8 (1)求抛物线与坐标轴交点A,B,C的坐标 (2)若抛物线顶点为D,与X轴交点A,B,求△ABC的面积
已知:抛物线y=x²-2x-8 (1)求抛物线与坐标轴交点A,B,C的坐标 (2)若抛物线顶点为D,与X轴交点A,B,求△ABC的面积
(1)∵抛物线y=x^2-2x-8
则令y=0,得x1=4,x2=-2
令x=0,得y=-8
∴抛物线与坐标轴交点A、B、C的坐标分别是A(4,0)、B(-2,0)、C(0,-8)
(2)∵抛物线y=x^2-2x-8 ==>y-(-9)=(x-1)^2
∴此抛物线顶点D的坐标是D(1,-9)
∵抛物线与x轴的交点是A(4,0)、B(-2,0)
∴△ABC的面积=(1/2)(0-(-9))(4-(-2))=27.