问题
选择题
命题p：∀x∈R，函数f(x)=2cos2x+
|
答案
y=2cos2x+
| 3 |
=1+cos2x+
| 3 |
=1+2(
| 1 |
| 2 |
| ||
| 2 |
=1+2sin(2x+
| π |
| 6 |
故命题p为真，
又∵命题p：∀x∈R，函数f(x)=2cos2x+
| 3 |
则￢p为：∃x∈R，f(x)=2cos2x+
| 3 |
故选D．
搜题请搜索小程序“爱下问搜题”
命题p：∀x∈R，函数f(x)=2cos2x+
|
y=2cos2x+
| 3 |
=1+cos2x+
| 3 |
=1+2(
| 1 |
| 2 |
| ||
| 2 |
=1+2sin(2x+
| π |
| 6 |
故命题p为真，
又∵命题p：∀x∈R，函数f(x)=2cos2x+
| 3 |
则￢p为：∃x∈R，f(x)=2cos2x+
| 3 |
故选D．