Question

Quy đồng mẫu số các phân số.

a) \(\dfrac{2}{5};\dfrac{13}{15}\) và \(\dfrac{19}{45}\)                            b) \(\dfrac{1}{2};\dfrac{3}{8};\dfrac{5}{4}\) và \(\dfrac{7}{16}\)

Answer 1

\(a)\) Mẫu số chung: 45.

\(\dfrac{2}{5}=\dfrac{2\times7}{5\times7}=\dfrac{14}{45}\\ \dfrac{13}{15}=\dfrac{13\times3}{15\times3}=\dfrac{39}{45}\\ \dfrac{19}{45}\)

b) Mẫu số chung: 16.

\(\dfrac{1}{2}=\dfrac{1\times8}{2\times8}=\dfrac{8}{16}\\ \dfrac{3}{8}=\dfrac{3\times2}{8\times2}=\dfrac{6}{16}\\ \dfrac{5}{4}=\dfrac{5\times4}{4\times4}=\dfrac{\dfrac{20}{16}\\ 7}{16}\)