Cho
;
. Tính
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019101968061839091/obj2019101968061839091693651_images/obj2019101968061839091693651_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019101968061839091/obj2019101968061839091693651_images/obj2019101968061839091693651_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/2019101968061839091/obj2019101968061839091693651_images/obj2019101968061839091693651_img3.png)
A.
.
B.
.
C.
.
D.
.
Đáp án và lời giải
Đáp án:C
Lời giải:
Phân tích: Ta có:
. Nên
. Ta có:
. Nên
. Vậy
.
Vậy đáp án đúng là C.