Question

Quy đồng mẫu số

a) 4/9 và 5/7; b) 7/12 và 3/4; c) 13/27,1/3 và 5/9

Answer 1

\(a,\dfrac{4}{9};\dfrac{5}{7}\left(MSC=63\right)\)

\(\dfrac{4}{9}=\dfrac{4\times7}{9\times7}=\dfrac{28}{63}\)

\(\dfrac{5}{7}=\dfrac{5\times9}{7\times9}=\dfrac{45}{63}\)

\(b,\dfrac{7}{12};\dfrac{3}{4}\left(MSC=12\right)\)

\(\dfrac{7}{12}\) giữ nguyên

\(\dfrac{3}{4}=\dfrac{3\times3}{4\times3}=\dfrac{9}{12}\)

\(c,\dfrac{13}{27};\dfrac{1}{3}\) và \(\dfrac{5}{9}\left(MSC=27\right)\)

\(\dfrac{13}{27}\) giữ nguyên

\(\dfrac{1}{3}=\dfrac{1\times9}{3\times9}=\dfrac{9}{27}\)

\(\dfrac{5}{9}=\dfrac{5\times3}{9\times3}=\dfrac{15}{27}\)

Answer 2