Gọi
là tập nghiệm của phương trình
. Mệnh đề nào dưới đây đúng?
A.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567575005_images/obj20191419675213726567575005_img1.png)
B.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567432500_images/obj20191419675213726567432500_img1.png)
C.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567754373_images/obj20191419675213726567754373_img1.png)
D.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567611868_images/obj20191419675213726567611868_img1.png)
Đáp án và lời giải
Đáp án:A
Lời giải:Phân tích:
Xét phương trình:
,
Vậy
.
Vậy đáp án đúng là A.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567596337_images/obj20191419675213726567596337_img1.png)
![img2](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567596337_images/obj20191419675213726567596337_img2.png)
![img3](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567596337_images/obj20191419675213726567596337_img3.png)
![img4](https://cungthi.online/upload/questionbank3/eduquestion/20191419675213726567/obj20191419675213726567596337_images/obj20191419675213726567596337_img4.png)