A=1/1.2.3+1/2.3.4+1/3.4.5+1/2014.2015.2016 SO SÁNH 1/4

0 bình luận về “A=1/1.2.3+1/2.3.4+1/3.4.5+1/2014.2015.2016 SO SÁNH 1/4”

1. $A$=$\dfrac{1}{1×2×3}$+$\dfrac{1}{2×3×4}$+….+ $\dfrac{1}{2014×2015×2016}$

   $⇒2A$=$\dfrac{2}{1×2×3}$+$\dfrac{2}{2×3×4}$+…+ $\dfrac{2}{2014×2015×2016}$

   $⇒2A$= $\dfrac{1}{1×2}$-$\dfrac{1}{2×3}$+ $\dfrac{1}{2×3}$+..+  $\dfrac{1}{2014×2015}$- $\dfrac{1}{2015×2016}$  

   $⇒2A$=$\dfrac{1}{2}$- $\dfrac{1}{2015×2016}$ 

   $⇒A$=($\dfrac{1}{2}$- $\dfrac{1}{2015×2016}$)÷2

   $⇒A$=$\dfrac{1}{4}$- $\dfrac{1}{2015×2016}$ 

   $⇒A<$ $\dfrac{1}{4}$

   $\text{Cho mình câu trả lời hay nhất}$

   Bình luận