Trong các khai triển sau, khai triển nào sai?
A.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2019571967728647927/obj2019571967728647927797472_images/obj2019571967728647927797472_img1.png)
B.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2019571967728647927/obj2019571967728647927509527_images/obj2019571967728647927509527_img1.png)
C.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2019571967728647927/obj2019571967728647927512462_images/obj2019571967728647927512462_img1.png)
D.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2019571967728647927/obj2019571967728647927369957_images/obj2019571967728647927369957_img1.png)
Đáp án và lời giải
Đáp án:C
Lời giải:Phân tích:
Ta có khai triển ở đáp án C là sai vì
phải chạy từ
trở đi.
Vậy đáp án đúng là C.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2019571967728647927/obj2019571967728647927577382_images/obj2019571967728647927577382_img1.png)
![img2](https://cungthi.online/upload/questionbank3/eduquestion/2019571967728647927/obj2019571967728647927577382_images/obj2019571967728647927577382_img2.png)