Question

Tính bằng cách thuân tiện nhất 

A. 14/15 * 23/21 * 15/23

B. 1/2 * 9/10 + 1/2 * 8/10 - 1/2 * 7/10

Answer 1

A. = 14/15 * 15/23 * 23/21

     = 14/23 * 23/21

      = 14/21

B. = 1/2 * (9/10 + 8/10 - 7/10)

     = 1/2 * 10/10

      = 1/2 * 1

       = 1/2

Answer 2

a) \(\frac{14}{15}\cdot\frac{23}{21}\cdot\frac{15}{23}=\frac{14}{21}=\frac{2}{3}\)

b)\(\frac{1}{2}\cdot\frac{9}{10}+\frac{1}{2}\cdot\frac{8}{10}-\frac{1}{2}\cdot\frac{7}{10}=\frac{1}{2}\cdot\left(\frac{9}{10}+\frac{8}{10}-\frac{7}{10}\right)=\frac{1}{2}\cdot1=\frac{1}{2}\)