3x²-5|x|-12≤0解不等式

3x²-5|x|-12≤0解不等式
3x²-5|x|-12≤0解不等式

3x²-5|x|-12≤0解不等式
3x²-5|x|-12=3|x|^2-5|x|-12<=0
(3|x|+4)(|x|-3)<=0
|x|-3<=0
|x|<=3
-3<=x<=3

x^2=|x|^2
则原不等式等价于
(3|x|+4)(|x|-3)<=0
则|x|-3<=0
则-3<=x<=3