Question

|4-X²|≤2 求X的取值范围

如题，请详细描述计算过程，本人数学小白，正在学习~谢啦~~

Answer 1

因为X²恒为正数。。所以上式就可以去掉绝对值符号就为4-X²≤2所以推出X²>=2。。然后就知道答案是负无穷到负根号2和根号2到正无穷。。

Answer 2

-2<=4-x^2<=2
-6<=-x^2<=-2
2<=x^2<=6
∴x大于等于负根6小于等于负根2或x大于等于根2小于等于根6

Answer 3

答：

|4-x^2|<=2
|x^2-4|<=2
-2<=x^2-4<=2
4-2<=x^2-4+4<=2+4
2<=x^2<=6
所以：
-√6<=x<=-√2或者√2<=x<=√6