[2D2-5.2-2] Gọi
là nghiệm của phương trình
. Giá trị của biểu thức
bằng
A.
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358409017_images/obj20202808923042715358409017_img1.png)
B.
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358220058_images/obj20202808923042715358220058_img1.png)
C.
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358706623_images/obj20202808923042715358706623_img1.png)
D.
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358198727_images/obj20202808923042715358198727_img1.png)
Đáp án và lời giải
Đáp án:A
Lời giải:
ĐKXĐ:
.
Khi đó
. Kết hợp với điều kiện xác định ta có
.
Do đó
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358846262_images/obj20202808923042715358846262_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358846262_images/obj20202808923042715358846262_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358846262_images/obj20202808923042715358846262_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358846262_images/obj20202808923042715358846262_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358846262_images/obj20202808923042715358846262_img5.png)
![img6](https://cungthi.online/upload/questionbank3_20201220/eduquestion/20202808923042715358/obj20202808923042715358846262_images/obj20202808923042715358846262_img6.png)