Question

mog mn giúp em ạ , cảm ơn 

Answer 1

\(a,\\ =\dfrac{10.11+10.5+11.5+10.7+11.7}{11.12+11.5+12.5+11.7+12.7}\\ =\dfrac{10.11\left(1+5.5+7.7\right)}{11.12\left(1+5.5+7.7\right)}=\dfrac{10}{12}=\dfrac{5}{6}\) 

\(b,\\ =\dfrac{\left(1.2.3.....25\right).\left(25.26.27....49\right)}{26.27.28.....50}\\ =\dfrac{1.2.3....25}{50}=1.2.3....12\)