Question

Quy đồng mẫu những phân số sau:

a) \(\dfrac{-5}{14}\) và \(\dfrac{1}{-21};\)                            b) \(\dfrac{17}{60};\dfrac{-5}{18};\dfrac{-64}{90}.\)

Answer 1

a) \(-\dfrac{5}{14}=-\dfrac{5.3}{14.3}=-\dfrac{15}{42}\)

\(\dfrac{1}{-21}=-\dfrac{1}{21}=-\dfrac{1.2}{21.2}=-\dfrac{2}{42}\)

b) \(\dfrac{17}{60}=\dfrac{17.3}{60.3}=\dfrac{51}{180}\)

\(\dfrac{-5}{18}=\dfrac{-5.10}{18.10}=-\dfrac{50}{180}\)

\(-\dfrac{64}{90}=-\dfrac{64.2}{90.2}=-\dfrac{128}{180}\)

Answer 2

a)-5/14 và 1/-21

-5/14=-5.-21/14.-2=105/-28

Answer 3

-64/90=-32/45=-32*4/45*4=-128/180