a) \(\dfrac{2}{5}+\dfrac{11}{15}=\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)
b) \(\dfrac{7}{8}-\dfrac{7}{9}=\dfrac{63}{72}-\dfrac{56}{72}=\dfrac{7}{72}\)
c) \(\dfrac{11}{13}\cdot\dfrac{26}{31}=\dfrac{26}{13}\cdot\dfrac{11}{31}=\dfrac{22}{31}\)
d) \(\dfrac{1}{2}:\dfrac{1}{3}\cdot\dfrac{2}{5}=\dfrac{1}{2}\cdot3\cdot\dfrac{2}{5}=\dfrac{3}{5}\)
a ) 2/5 + 11/15 = 6/15 + 11/ 15 = 17/15.
b ) 7/8 -7/9 = 63/72 -56/72 = 7/72.
c ) 11/13 x 26/31 = 22/31
d ) 1/2 : 1/3 x 2/5= 1/2 x 3/1 x 2/5 = 3/5
đúng thì tick mình nhé!!! cảm ơn bạn