Giải thích các bước giải:
Ta có:
$B=\dfrac71+\dfrac26+\dfrac35+\dfrac44+\dfrac53+\dfrac62+\dfrac17$
$\to B=7+\dfrac26+\dfrac35+\dfrac44+\dfrac53+\dfrac62+\dfrac17$
$\to B=(\dfrac17+1)+(\dfrac26+1)+(\dfrac35+1)+(\dfrac44+1)+(\dfrac53+1)+(\dfrac62+1)+1$
$\to B=\dfrac{7+1}7+\dfrac{2+6}6+\dfrac{3+5}5+\dfrac{4+4}4+\dfrac{5+3}3+\dfrac{6+2}2+1$
$\to B=\dfrac{8}7+\dfrac{8}6+\dfrac{8}5+\dfrac{8}4+\dfrac{8}3+\dfrac{8}2+\dfrac88$
$\to B=8(\dfrac17+\dfrac16+\dfrac15+\dfrac14+\dfrac13+\dfrac12+\dfrac18)$
$\to B=8(\dfrac12+\dfrac13+\dfrac14+\dfrac15+\dfrac16+\dfrac17+\dfrac18)$
$\to B=8A$
