D= (13/23+13/203-99/100).(1/3+1/7-10/21)

Giải thích các bước giải:

D = ($\frac{13}{23}$ + $\frac{13}{203}$ - $\frac{99}{100}$).( $\frac{1}{3}$ + $\frac{1}{7}$ - $\frac{10}{21}$ )

⇒ D = ($\frac{13}{23}$ + $\frac{13}{203}$ - $\frac{99}{100}$). ( $\frac{7}{21}$ + $\frac{3}{21}$ - $\frac{10}{21}$ )

⇔ D = ($\frac{13}{23}$ + $\frac{13}{203}$ - $\frac{99}{100}$). ( $\frac{10}{21}$ - $\frac{10}{21}$ )

⇔ D = ($\frac{13}{23}$ + $\frac{13}{203}$ - $\frac{99}{100}$). 0

⇒ D = 0

                           Vậy D = 0