Question

2/3x5+2/5x7+...+2/17x19

Answer 1

\(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{17.19}\)

= \(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{17}-\frac{1}{19}\)

= \(\frac{1}{3}-\frac{1}{19}\)

= \(\frac{16}{57}\)

Answer 2

\(\frac{2}{3.5}+\frac{2}{5.7}+.....+\frac{2}{17.19}\)

\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+.....+\frac{1}{17}-\frac{1}{19}\)

\(=\frac{1}{3}-\frac{1}{19}\)

\(=\frac{19}{57}-\frac{3}{57}\)

\(=\frac{16}{57}\)

vậy ......

chúc bạn học tốt!

Answer 3

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Answer 4

Trl 

=1/3-1/19

=16/57

Answer 5

Trả lời 

1/3-1/9=16/57

chúc bn 

học tốt

Answer 6

=16/57

hk tốt

>.<

Answer 7

Trl

=19/57-3/57=16/57

Chúc bn 

Hok tốt 

Answer 8

\(\frac{2}{3.5}+\frac{2}{5.7}+....+\frac{2}{17.19}\)

\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{17}\)\(-\frac{1}{19}\)

\(=\frac{1}{3}-\frac{1}{19}=\frac{16}{57}\)