Cho
,
. Tính
theo
,
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019533175070212226/obj2019533175070212226927617_images/obj2019533175070212226927617_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019533175070212226/obj2019533175070212226927617_images/obj2019533175070212226927617_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019533175070212226/obj2019533175070212226927617_images/obj2019533175070212226927617_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019533175070212226/obj2019533175070212226927617_images/obj2019533175070212226927617_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019533175070212226/obj2019533175070212226927617_images/obj2019533175070212226927617_img5.png)
A.
B.
C.
D.
Đáp án và lời giải
Đáp án:B
Lời giải:
Phân tích: Ta có
.
Đáp án đúng là B.