已知函数fx x
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已知函数fx x
![已知函数fx x](/uploads/image/z/17485831-55-1.jpg?t=%E5%B7%B2%E7%9F%A5%E5%87%BD%E6%95%B0fx+x)
答:
x<=0,f(x)=x+2
x>0,f(x)=-x+2
函数f(x)是两条射线,见简图如下
不等式f(x)>=x^2>=0
显然,从图像可以看出:-2<=x<=2时,f(x)>=0
1)当x<=0时:f(x)=x+2>=x^2
x^2-x-2<=0
(x-2)(x+1)<=0
-1<=x<=2
所以:-1<=x<=0
2)当x>0时:f(x)=-x+2>=x^2
x^2+x-2<=0
(x+2)(x-1)<=0
-2<=x<=1
所以:0<x<=1
综上所述,不等式f(x)>=x^2的解集为[-1,1]
![](http://img.wesiedu.com/upload/e/62/e6216db3296550f31cf6e441f7fa383f.jpg)
x<=0,f(x)=x+2
x>0,f(x)=-x+2
函数f(x)是两条射线,见简图如下
不等式f(x)>=x^2>=0
显然,从图像可以看出:-2<=x<=2时,f(x)>=0
1)当x<=0时:f(x)=x+2>=x^2
x^2-x-2<=0
(x-2)(x+1)<=0
-1<=x<=2
所以:-1<=x<=0
2)当x>0时:f(x)=-x+2>=x^2
x^2+x-2<=0
(x+2)(x-1)<=0
-2<=x<=1
所以:0<x<=1
综上所述,不等式f(x)>=x^2的解集为[-1,1]
![](http://img.wesiedu.com/upload/e/62/e6216db3296550f31cf6e441f7fa383f.jpg)