a: 3/7=15/35
2/5=14/35
b: -3/4=-18/24
1/6=4/24
5/8=15/24
c: \(-\dfrac{2}{3^2\cdot5^3}=\dfrac{-2\cdot3}{3^3\cdot5^3}=\dfrac{-6}{15^3}\)
\(\dfrac{4}{3^3\cdot5^2}=\dfrac{4\cdot5}{3^3\cdot5^3}=\dfrac{20}{15^3}\)
\(a,ta.c\text{ó}:BCNN\left(7;5\right)=35\\ \dfrac{3}{7}=\dfrac{3\times5}{7\times5}=\dfrac{15}{35};\dfrac{2}{5}=\dfrac{2\times7}{5\times7}=\dfrac{14}{35}\)