# GRE Question of the Day (September 11)

- Sep 11, 02:00 AM Comments [0]

## Math

The sequence of numbers $${a_1}$$, $${a_2}$$, $${a_3}$$, . . . , $${a_n}$$, . . . is defined by $${a_n}$$$${= \frac{{1}}{{n}} - \frac{{1}}{{(n+2)}}}$$ for each integer $${n ≥ 1}$$. What is the sum of the first 20 terms of this sequence?

A. $${(1+\frac{{1}}{{2}}) - \frac{{1}}{{20}}}$$

B. $${(1+\frac{{1}}{{2}}) - (\frac{{1}}{{21}}+\frac{{1}}{{22}})}$$

C. $${1 - (\frac{{1}}{{20}}+\frac{{1}}{{22}})}$$

D. $${1 - \frac{{1}}{{22}}}$$

E. $${\frac{{1}}{{20}} - \frac{{1}}{{22}}}$$

Question Discussion & Explanation