Question

tính giá trị của biểu thức

A = 2/3 + 2/5 - 2/9

4/3 + 4/5 - 4/9

Answer 1

A = 2/3 + 2/5 - 2/9

= 6/9 + 2/5 - 2/9

= (6/9 - 2/9) + 2/5

= 4/9 + 2/5 = 38/45

4/3 + 4/5 - 4/9

= 12/9 + 4/5 - 4/9

= (12/9 - 4/9) + 4/5

= 8/9 + 4/5 = 76/45

đúng ko thế ?

Answer 2

\(\dfrac{\dfrac{2}{3}+\dfrac{2}{5}-\dfrac{2}{9}}{\dfrac{4}{3}+\dfrac{4}{5}-\dfrac{4}{9}}=\dfrac{\dfrac{2}{3}+\dfrac{2}{5}-\dfrac{2}{9}}{2\left(\dfrac{2}{3}+\dfrac{2}{5}-\dfrac{2}{9}\right)}=\dfrac{1}{2}\)