Question

Tính nhanh

A=4/3*5+4/5*7+4/7*9+4/9*11

Answer 1

= 5/7.(5/11-2/11-14/4)

=5/7.(-71/22)= -355/154

Answer 2

A=\(\frac{5}{7}\)x\(\frac{5}{11}\)-\(\frac{5}{7}\)x\(\frac{2}{11}\)-\(\frac{5}{7}\)x\(\frac{14}{4}\)

A= \(\frac{5}{7}\)x(\(\frac{5}{11}\)-\(\frac{2}{11}\)-\(\frac{14}{4}\))

A=\(\frac{5}{7}\)x(\(\frac{3}{11}\)-\(\frac{14}{4}\))

A=\(\frac{5}{7}\)x\(\frac{-71}{22}\)

A=\(\frac{-355}{154}\)