已知抛物线y=x²-3x+c与x轴有交点(1)求c的取值范围(2)若抛物线与x轴的两个交点为A(x1,0)、(x2,0),满足x1<0<x2且OB=2OA,求此时c的值
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/27 02:31:20
![已知抛物线y=x²-3x+c与x轴有交点(1)求c的取值范围(2)若抛物线与x轴的两个交点为A(x1,0)、(x2,0),满足x1<0<x2且OB=2OA,求此时c的值](/uploads/image/z/8618380-52-0.jpg?t=%E5%B7%B2%E7%9F%A5%E6%8A%9B%E7%89%A9%E7%BA%BFy%3Dx%26%23178%3B-3x%2Bc%E4%B8%8Ex%E8%BD%B4%E6%9C%89%E4%BA%A4%E7%82%B9%EF%BC%881%EF%BC%89%E6%B1%82c%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4%EF%BC%882%EF%BC%89%E8%8B%A5%E6%8A%9B%E7%89%A9%E7%BA%BF%E4%B8%8Ex%E8%BD%B4%E7%9A%84%E4%B8%A4%E4%B8%AA%E4%BA%A4%E7%82%B9%E4%B8%BAA%EF%BC%88x1%2C0%EF%BC%89%E3%80%81%EF%BC%88x2%2C0%EF%BC%89%2C%E6%BB%A1%E8%B6%B3x1%EF%BC%9C0%EF%BC%9Cx2%E4%B8%94OB%3D2OA%2C%E6%B1%82%E6%AD%A4%E6%97%B6c%E7%9A%84%E5%80%BC)
xQJ@A!I<@A.V݈
.T\_4]ɣQtFpu2Lﳋiz0ܫ,|duTHۊcRύC?=-"-"7Y~2>M(?K&3`KRLquaa ewYy#ϗ=िn~O+[?=vonK?P{40-$5ؼ@fO$wao">J
nT*kTq M@2
)"
ք6
^Ƥj5D<a5b"SSZ
K;-}{$=
已知抛物线y=x²-3x+c与x轴有交点(1)求c的取值范围(2)若抛物线与x轴的两个交点为A(x1,0)、(x2,0),满足x1<0<x2且OB=2OA,求此时c的值
已知抛物线y=x²-3x+c与x轴有交点
(1)求c的取值范围
(2)若抛物线与x轴的两个交点为A(x1,0)、(x2,0),满足x1<0<x2且OB=2OA,求此时c的值
已知抛物线y=x²-3x+c与x轴有交点(1)求c的取值范围(2)若抛物线与x轴的两个交点为A(x1,0)、(x2,0),满足x1<0<x2且OB=2OA,求此时c的值
(1)
与x轴有交点,x²-3x+c = 0的判别式9-4c ≥ 0,c ≤ 9/4
(2)
x₂ = -2x₁,x₁ < 0
y = (x - x₁)(x - x₂) = (x - x₁)(x + 2x₁) = x² + x₁x - 2x₁² = x² - 3x + c
x₁ = -3
c = -2x₁² = -18