Với mọi
,
,
là các số thực dương thoả mãn
. Mệnh đề nào dưới đây đúng?
A.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20192012860313472211/obj20192012860313472211966310_images/obj20192012860313472211966310_img1.png)
B.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20192012860313472211/obj20192012860313472211253854_images/obj20192012860313472211253854_img1.png)
C.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20192012860313472211/obj20192012860313472211826740_images/obj20192012860313472211826740_img1.png)
D.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20192012860313472211/obj20192012860313472211761750_images/obj20192012860313472211761750_img1.png)
Đáp án và lời giải
Đáp án:D
Lời giải:Phân tích:
Có
.
Vậy đáp án đúng là D.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20192012860313472211/obj20192012860313472211572722_images/obj20192012860313472211572722_img1.png)