13-6

In advanced math this week we started chapter 13. I found that chapter 13 was very hard. However, the easiest section was section 13-6. This section is about a symbol called sigma. A sigma is a series written in condensed form. Around the sigma are its index, summand and limits of summation. The two main things you do with sigma is evaluate and expand it. Let’s try a few examples.

Example 1:

Identify

6
∑4k
K = 2

Find the Summand? 4k
What is the index? k
What are the limits of summation? 5 and 2

Evaluate the Sigma

4(2) + 4(3) + 4(4) + 4(5) + 4(6)
8 + 12 + 16+ 20 + 24 = 80

Example 2:

Expand the Sigma

10
∑ 5k4
K = 3

5(3)4 + 5(4)4 + 5(5)4 + 5(6)4 + 5(7)4 + 5(8)4 + 5(9)4 + 5(10)4
405 + 1280 + 3125 + 6480 + 12005 + 20480 + 32805 + 50000