Question

已知函数fx=2x方+1(x小于等于0) fx=-2x(x大于0)则不等式fx-x≤2的解集为

Answer 1

x小于等于0
2x^2+1-x≤2
2x^2-x-1≤0
(x-1)(2x+1)≤0
-1/2≤x≤1
综上-1/2≤x≤0

x大于0
-2x-x≤2
3x≥-2
x≥-3/2
综上x>0

综上x≥-1/2

Answer 2

x<=0
2x²+x-1<=2
(2x+3)(x-1)<=0
所以-3/2<=x<=0

x>0
-2x-x<=2
所以x>0

所以x>=-3/2

追问

哥们，你弄错了吧 2x²+x-1<=2 这部错了吧应该是2x²-x+1<=2吧

追答

哦
(2x+1)(x-1)=-1/2

Answer 3

-1/2≤x≤0或x≥2/3

追问

哥们，-2x-x≤2，解出来的解集是正的？？

追答

错啦错啦……x＞0
也就是-1/2≤x