函数f(x)=-x²-4x+1的零点为___________________A.-1+((√2)/2)B.-1-((√6)/2)C.-1±((√6)/2)D.不存在以下是我分析的,Δ=20>0 两个零点-x²-4x+1=0(x+2)²=5x=-2±√5是不是答案有误?
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![函数f(x)=-x²-4x+1的零点为___________________A.-1+((√2)/2)B.-1-((√6)/2)C.-1±((√6)/2)D.不存在以下是我分析的,Δ=20>0 两个零点-x²-4x+1=0(x+2)²=5x=-2±√5是不是答案有误?](/uploads/image/z/10180940-68-0.jpg?t=%E5%87%BD%E6%95%B0f%28x%29%3D-x%26%23178%3B-4x%2B1%E7%9A%84%E9%9B%B6%E7%82%B9%E4%B8%BA___________________A.-1%2B%28%28%E2%88%9A2%29%2F2%29B.-1-%28%28%E2%88%9A6%29%2F2%29C.-1%C2%B1%28%28%E2%88%9A6%29%2F2%29D.%E4%B8%8D%E5%AD%98%E5%9C%A8%E4%BB%A5%E4%B8%8B%E6%98%AF%E6%88%91%E5%88%86%E6%9E%90%E7%9A%84%2C%CE%94%3D20%3E0+%E4%B8%A4%E4%B8%AA%E9%9B%B6%E7%82%B9-x%26%23178%3B-4x%2B1%3D0%28x%2B2%29%26%23178%3B%3D5x%3D-2%C2%B1%E2%88%9A5%E6%98%AF%E4%B8%8D%E6%98%AF%E7%AD%94%E6%A1%88%E6%9C%89%E8%AF%AF%3F)
函数f(x)=-x²-4x+1的零点为___________________A.-1+((√2)/2)B.-1-((√6)/2)C.-1±((√6)/2)D.不存在以下是我分析的,Δ=20>0 两个零点-x²-4x+1=0(x+2)²=5x=-2±√5是不是答案有误?
函数f(x)=-x²-4x+1的零点为___________________
A.-1+((√2)/2)
B.-1-((√6)/2)
C.-1±((√6)/2)
D.不存在
以下是我分析的,
Δ=20>0 两个零点
-x²-4x+1=0
(x+2)²=5
x=-2±√5
是不是答案有误?
函数f(x)=-x²-4x+1的零点为___________________A.-1+((√2)/2)B.-1-((√6)/2)C.-1±((√6)/2)D.不存在以下是我分析的,Δ=20>0 两个零点-x²-4x+1=0(x+2)²=5x=-2±√5是不是答案有误?
-x²-4x+1
=-x²-4x-4+5
=-(x²+4x+4)+5
=-(x+2)²+5
令-(x+2)²+5=0
有,±√5=x+2
即x=-2±√5
答案有误.
答案有误,我算出来和你一样的
直接令函数等于0 解得答案是正负根号3 +2