Question

[Vũ Trí Dũng]

4/3x7 + 5/7x12 + 1/12x13 + 7/13x20 + 3/20x23

Answer 1

[Bùi Mạnh Hải]

A = \(\dfrac{4}{3.7}\) + \(\dfrac{5}{7.12}\) + \(\dfrac{1}{12.13}\) + \(\dfrac{7}{13.20}\) + \(\dfrac{3}{20.23}\)

A = \(\dfrac{1}{3}\) - \(\dfrac{1}{7}\) + \(\dfrac{1}{7}\) - \(\dfrac{1}{12}\) + \(\dfrac{1}{12}\) - \(\dfrac{1}{13}\) + \(\dfrac{1}{13}\) - \(\dfrac{1}{20}\) + \(\dfrac{1}{20}\)- \(\dfrac{1}{23}\)

A = \(\dfrac{1}{3}\) - \(\dfrac{1}{23}\)

A = 20/69

Answer 2

[Do Chiem Thinh phat]

A = $\genfrac{}{}{0ex}{}{4}{3.7}$ + $\genfrac{}{}{0ex}{}{5}{7.12}$ + $\genfrac{}{}{0ex}{}{1}{12.13}$ + $\genfrac{}{}{0ex}{}{7}{13.20}$ + $\genfrac{}{}{0ex}{}{3}{20.23}$

A = $\genfrac{}{}{0ex}{}{1}{3}$ - $\genfrac{}{}{0ex}{}{1}{7}$ + $\genfrac{}{}{0ex}{}{1}{7}$ - $\genfrac{}{}{0ex}{}{1}{12}$ + $\genfrac{}{}{0ex}{}{1}{12}$ - $\genfrac{}{}{0ex}{}{1}{13}$ + $\genfrac{}{}{0ex}{}{1}{13}$ - $\genfrac{}{}{0ex}{}{1}{20}$ + $\genfrac{}{}{0ex}{}{1}{20}$- $\genfrac{}{}{0ex}{}{1}{23}$

A = $\genfrac{}{}{0ex}{}{1}{3}$ - $\genfrac{}{}{0ex}{}{1}{23}$