那儿无痛人流手术最好:如何解不等式2x2+ax+2>0

来源:百度文库 编辑:查人人中国名人网 时间:2024/05/05 19:55:34

2x^2 + ax + 2 > 0
x^2 + a/2*x + 1 > 0

x^2 + a/2*x + 1
= (x^2 + 2*a/4*x + a^2/16) + (1 - a^2/16)
= (x + a/4)^2 + (1 - a^2/16)
>= (1 - a^2/16)
> 0

1 > a^2/16

|a| < 4

2x^2 + ax + 2 > 0
x^2 + a/2*x + 1 > 0

x^2 + a/2*x + 1
= (x^2 + 2*a/4*x + a^2/16) + (1 - a^2/16)
= (x + a/4)^2 + (1 - a^2/16)
>= (1 - a^2/16)
> 0

1 > a^2/16

|a| < 4

分a=0;a>0;a<0三种情况讨论