Express the sum using summation notation.
-3 + 12 + 27 + . . . + 108

Question

Quizplus · Accepted Answer

The sequence is increasing by 3 each time, starting with 3. Therefore, we can represent it using the sum of an arithmetic series as: 
$$\sum_{i=1}^{10}(3i)$$
This notation represents the sum of each term in the sequence from the first term (3) to the 10th term (which is 3*10 = 30), where $i$ is the index of the current term. Simplifying the expression, we get: 
$$3\sum_{i=1}^{10}i$$
Which is equivalent to: 
$$3\cdot\frac{(10)(11)}{2}$$
Simplifying further, we get the sum as  165.

Express the Sum Using Summation Notation