Đáp án:
Giải thích các bước giải:
$\dfrac{\dfrac{1}{3}+\dfrac{1}{9}-\dfrac{1}{27}}{\dfrac{5}{3}+\dfrac{5}{9}-\dfrac{5}{27}}$
`=`$\dfrac{1.(\dfrac{1}{3}+\dfrac{1}{9}-\dfrac{1}{27})}{5.(\dfrac{5}{3}+\dfrac{5}{9}-\dfrac{5}{27})}$
`=1/5.`$\dfrac{\dfrac{1}{3}+\dfrac{1}{9}-\dfrac{1}{27}}{\dfrac{1}{3}+\dfrac{1}{9}-\dfrac{1}{27}}$
`=1/5 .1=1/5`