Giải thích các bước giải:
Ta có:
$9S=4-\dfrac{2014}{4^{2013}}-\dfrac{1}{4^{2013}}+\dfrac{2014}{4^{2014}}$
$\to 9S=4-\dfrac{2014\cdot 4}{4^{2013}\cdot 4}-\dfrac{1\cdot 4}{4^{2013}\cdot 4}+\dfrac{2014}{4^{2014}}$
$\to 9S=4-\dfrac{8056}{4^{2013+1}}-\dfrac{ 4}{4^{2013+1}}+\dfrac{2014}{4^{2014}}$
$\to 9S=4-\dfrac{8056}{4^{2014}}-\dfrac{4}{4^{2014}}+\dfrac{2014}{4^{2014}}$
$\to 9S=4-(\dfrac{8056}{4^{2014}}+\dfrac{4}{4^{2014}}-\dfrac{2014}{4^{2014}})$
$\to 9S=4-\dfrac{8056+4-2014}{4^{2014}}$
$\to 9S=4-\dfrac{6046}{4^{2014}}$
$\to 9S<4$
$\to S<\dfrac49<1$
