Express the sum using summation notation.
-$$\sum _ { k = 1 } ^ { 4 } \frac { 1 } { 7 k }$$
A) $\frac { 1 } { 28 }$
B) $\frac { 11 } { 42 }$
C) $\frac { 5 } { 28 }$
D) $\frac { 25 } { 84 }$

Question

Quizplus · Accepted Answer

The given sum can be calculated directly: $\frac{1}{7} + \frac{1}{14} + \frac{1}{21} + \frac{1}{28} = \frac{1}{7}(1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4}) = \frac{1}{7} \cdot \frac{25}{12} = \frac{25}{84}$.

Express the Sum Using Summation Notation ∑k=1417k\sum _ { k = 1 } ^ { 4 } \frac { 1 } { 7 k }k=1∑4​7k1​

Express the Sum Using Summation Notation $\sum _ { k = 1 } ^ { 4 } \frac { 1 } { 7 k }$