1.(x+1)(x-2)＞0
x＜-1或x＞2
2.x平方-4x+3＞0
(x-1)(x-3)＞0
x＜1或x＞3
3.-2x平方+x+3＞0
2x²-x-3＜0
(x+1)(2x-3)＜0
-1＜x＜3/2
4.4x平方+4x+1大于等于0
(2x+1)²≥0
x是任意实数