lm hộ em câu này dc ko ạ

Đáp án:

Ta có:

`B = (2015 + 2016 + 2017)/(2016 + 2017 + 2018)`

`= 2015/(2016 + 2017 + 2018) + 2016/(2016 + 2017 + 2018) + 2017/(2016 + 2017 + 2018)`

Nhận xét:

$\left.\begin{matrix} \dfrac{2015}{2016} > \dfrac{2015}{2016 + 2017 + 2018}\\\dfrac{2016}{2017} > \dfrac{2016}{2016 + 2017 + 2018}\\ \dfrac{2017}{2018} > \dfrac{2017}{2016 + 2017 + 2018} \end{matrix}\right\}$

`-> 2015/2016 + 2016/2017 + 2017/2018 > 2015/(2016 + 2017 + 2018) + 2016/(2016 + 2017 + 2018) + 2017/(2016 + 2017 + 2018)`

`-> 2015/2016 + 2016/2017 + 2017/2018 > (2015 + 2016 + 2017)/(2016 + 2017 + 2018)`

`-> A > B`

Vậy `A > B`

`#dariana`