[ Mức độ 3] Có bao nhiêu số thực m để hàm số
có giá trị lớn nhất trên đoạn
bằng
?
A. 4.
B. 0.
C. 2.
D. 1.
Đáp án và lời giải
Đáp án:D
Lời giải:
Xét
Khảo sát hàm số trên đoạn
ta được
;
.
Như vậy
Dấu = xẩy ra khi và chỉ khi
nên có 1 giá trị cần tìm.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img5.png)
![img6](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img6.png)
![img7](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img7.png)
![img8](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img8.png)
![img9](https://cungthi.online/upload/questionbank3_20201220/eduquestion/202028021084241186723/obj202028021084241186723846924_images/obj202028021084241186723846924_img9.png)