Question

Tính tổng nhanh

1/1*2+1/2*3+1/3*4+1/5*6

Answer 1

1/1*2+1/2*3+1/3*4+1/5*6

=1-1/2+1/2-1/3+1/3-1/4+1/5-1/6

=1-1/4+1/5-1/6

=47/60

Answer 2

\(\frac{1}{1}\cdot2+\frac{1}{2}\cdot3+\frac{1}{3}\cdot4+\frac{1}{5}\cdot6\)

\(=2+\frac{3}{2}+\frac{4}{3}+\frac{6}{5}\)

\(=\frac{181}{30}\)