Question

1/2+1/6+1/12+1/20+1/30=?

Answer 1

   1/2 + 1/6 + 1/12 + 1/20 + 1/30 

= 1/1.2 + 1/2.3 + 1/3.4 + 1/4.5 + 1/5.6 

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

= 1 - 1/6 

= 5/6 

Đúng cho mình nha 

Answer 2

\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)

=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{4.3}+\frac{1}{4.5}+\frac{1}{5.6}\)

=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

=\(1-\frac{1}{6}\)

=\(\frac{5}{6}\)