Cho
.
Tính phép toán
A.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2018061055991319374/obj2018061055991319374298510_images/obj2018061055991319374298510_img1.png)
B.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2018061055991319374/obj2018061055991319374837469_images/obj2018061055991319374837469_img1.png)
C.
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2018061055991319374/obj2018061055991319374487539_images/obj2018061055991319374487539_img1.png)
D.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2018061055991319374/obj2018061055991319374881057_images/obj2018061055991319374881057_img1.png)
Đáp án và lời giải
Đáp án:A
Lời giải:Phân tích:
Ta có:
.
Vậy đáp án đúng là A.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2018061055991319374/obj2018061055991319374974103_images/obj2018061055991319374974103_img1.png)
![img2](https://cungthi.online/upload/questionbank3/eduquestion/2018061055991319374/obj2018061055991319374974103_images/obj2018061055991319374974103_img2.png)