Question

问一道不等式怎么解

|1-x^2|<=1
答案是-√2到√2吧 自己算的是0到√2 以前学的忘光了

Answer 1

|1-x^2|<=1

-1<=1-x^2<=1

-2<=-x^2<=0
2>=x^2>=0，即x^2<=2和x^2>=0的交集，x^2>=0的解是全体实数R，x^2<=2的解集是-√2到√2，二者交集是 [-√2，√2]

Answer 2

-1<=1-x^2<=1
-2<=-x^2<=0
0<=x^2<=2
x^2<=2
-√2<=x<=√2

Answer 3

-1<=x^2-1<=1

0<=x^2<=2

-√2<=x<=√2

画图看一下就行了