Question

\(\frac{2}{1.2}+\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{100.101}=?\)

 

Answer 1

=2(1/1.2+1/2.3+...+1/100.101)

=2(1/1-1/2+1/2-...+1/100-1/101)

=2(1-1/101)

=2.100/101

=200/101

Answer 2

2/1.2+2/2.3+2/3.4+...+2/100.101

= 2(2/1.2+2/2.3+2/3.4+...+2/100.101)

= 2(1/1.2+1/2.3+1/3.4+...+1/100.101)

= 2(1/1-1/2+1/2-1/3+1/3-1/4+...+1/100-1/101)

= 2.(1/1-1/101)

= 2.100/101

= 200/101

Cho mình 1 đ-ú-n-g nha bạn