Toán 2/50.52+2/51.53+…+2/88.90 lẹ lên mình cần gấp nha 06/10/2021 By Valentina 2/50.52+2/51.53+…+2/88.90 lẹ lên mình cần gấp nha
Đáp án: $\begin{array}{l}A = \dfrac{2}{{50.52}} + \dfrac{2}{{51.53}} + \dfrac{2}{{52.54}} + … + \dfrac{2}{{88.90}}\\ = \dfrac{{52 – 50}}{{50.52}} + \dfrac{{53 – 51}}{{51.53}} + \dfrac{{54 – 52}}{{52.54}} + … + \dfrac{{90 – 88}}{{88.90}}\\ = \dfrac{1}{{50}} – \dfrac{1}{{52}} + \dfrac{1}{{51}} – \dfrac{1}{{53}} + \dfrac{1}{{52}} – \dfrac{1}{{54}} + … + \dfrac{1}{{88}} – \dfrac{1}{{90}}\\ = \dfrac{1}{{50}} – \dfrac{1}{{90}}\\ = \dfrac{4}{{450}}\\ = \dfrac{2}{{225}}\end{array}$ Trả lời
Đáp án:
Giải thích các bước giải: cho mình câu trả lời hay nhất
Đáp án:
$\begin{array}{l}
A = \dfrac{2}{{50.52}} + \dfrac{2}{{51.53}} + \dfrac{2}{{52.54}} + … + \dfrac{2}{{88.90}}\\
= \dfrac{{52 – 50}}{{50.52}} + \dfrac{{53 – 51}}{{51.53}} + \dfrac{{54 – 52}}{{52.54}} + … + \dfrac{{90 – 88}}{{88.90}}\\
= \dfrac{1}{{50}} – \dfrac{1}{{52}} + \dfrac{1}{{51}} – \dfrac{1}{{53}} + \dfrac{1}{{52}} – \dfrac{1}{{54}} + … + \dfrac{1}{{88}} – \dfrac{1}{{90}}\\
= \dfrac{1}{{50}} – \dfrac{1}{{90}}\\
= \dfrac{4}{{450}}\\
= \dfrac{2}{{225}}
\end{array}$