Question

Áp dụng tính chất phép nhân để tính nhanh: 

C= 4/7.3/5.7/4.(-20).-11/12

 

Answer 1

\(C=\dfrac{4}{7}\cdot\dfrac{3}{5}\cdot\dfrac{7}{4}\cdot\left(-20\right)\cdot\dfrac{-11}{12}\)

\(=\dfrac{4}{4}\cdot\dfrac{7}{7}\cdot\dfrac{3}{5}\cdot20\cdot\dfrac{11}{12}\)

\(=12\cdot\dfrac{11}{12}=11\)

Answer 2

`#3107.101107`

\(C=\dfrac{4}{7}\cdot\dfrac{3}{5}\cdot\dfrac{7}{4}\cdot\left(-20\right)\cdot\left(-\dfrac{11}{12}\right)\\ =\left(\dfrac{4}{7}\cdot\dfrac{7}{4}\right)\cdot\left(-20\cdot\dfrac{3}{5}\right)\cdot\left(-\dfrac{11}{12}\right)\\ =1\cdot\left(-12\right)\cdot\left(-\dfrac{11}{12}\right)\\ =\left(-12\right)\cdot\left(-\dfrac{11}{12}\right)\\ =11\)