Question

（3）题（4）题怎么解

Answer 1

x²+2x+1＞0
（x+1）²＞0
x≠-1
（4）x²+2x-1＜0
x²+2x+1-2＜0
（x+1）²＜2
-√2＜x+1＜√2
-1-√2＜x＜√2-1

Answer 2

(3) (x+1)²>0
∵(x+1)²≥0
∴x≠-1

追答

(4)x² + 2x<1
x² + 2x + 1<1+1
(x+1)²<2
∴-1-√2<x<√2-1