已知抛物线C:y=-x²+mx-1,点A(3,0),B(0,3),求C与线段AB有两个不同焦点时m的取值范围( )线段AB:x+y-3=0(0≤x≤3)由方程组:x+y-3=0y=-x²+mx-1消去y,得x²-(m+1)x+4=0令f(x)=x²-(m+1)x+4则f(x)=0在[0,3]
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![已知抛物线C:y=-x²+mx-1,点A(3,0),B(0,3),求C与线段AB有两个不同焦点时m的取值范围( )线段AB:x+y-3=0(0≤x≤3)由方程组:x+y-3=0y=-x²+mx-1消去y,得x²-(m+1)x+4=0令f(x)=x²-(m+1)x+4则f(x)=0在[0,3]](/uploads/image/z/12478343-23-3.jpg?t=%E5%B7%B2%E7%9F%A5%E6%8A%9B%E7%89%A9%E7%BA%BFC%3Ay%3D-x%26%23178%3B%2Bmx-1%2C%E7%82%B9A%283%2C0%29%2CB%280%2C3%29%2C%E6%B1%82C%E4%B8%8E%E7%BA%BF%E6%AE%B5AB%E6%9C%89%E4%B8%A4%E4%B8%AA%E4%B8%8D%E5%90%8C%E7%84%A6%E7%82%B9%E6%97%B6m%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4%EF%BC%88+%EF%BC%89%E7%BA%BF%E6%AE%B5AB%EF%BC%9Ax%2By-3%3D0%280%E2%89%A4x%E2%89%A43%29%E7%94%B1%E6%96%B9%E7%A8%8B%E7%BB%84%EF%BC%9Ax%2By-3%3D0y%3D-x%26%23178%3B%2Bmx-1%E6%B6%88%E5%8E%BBy%2C%E5%BE%97x%26%23178%3B-%28m%2B1%29x%2B4%3D0%E4%BB%A4f%28x%29%3Dx%26%23178%3B-%28m%2B1%29x%2B4%E5%88%99f%28x%29%3D0%E5%9C%A8%5B0%2C3%5D)
已知抛物线C:y=-x²+mx-1,点A(3,0),B(0,3),求C与线段AB有两个不同焦点时m的取值范围( )线段AB:x+y-3=0(0≤x≤3)由方程组:x+y-3=0y=-x²+mx-1消去y,得x²-(m+1)x+4=0令f(x)=x²-(m+1)x+4则f(x)=0在[0,3]
已知抛物线C:y=-x²+mx-1,点A(3,0),B(0,3),求C与线段AB有两个不同焦点时m的取值范围( )
线段AB:x+y-3=0(0≤x≤3)
由方程组:x+y-3=0
y=-x²+mx-1
消去y,得x²-(m+1)x+4=0
令f(x)=x²-(m+1)x+4
则f(x)=0在[0,3]内有两个不同实数根的充要条件是
方程组:Δ=(m+1)²-4x1x4>0
0
已知抛物线C:y=-x²+mx-1,点A(3,0),B(0,3),求C与线段AB有两个不同焦点时m的取值范围( )线段AB:x+y-3=0(0≤x≤3)由方程组:x+y-3=0y=-x²+mx-1消去y,得x²-(m+1)x+4=0令f(x)=x²-(m+1)x+4则f(x)=0在[0,3]
对称轴(m+1)/2
在(0 ,3)之间啊