Because sigma notation is just a new way of writing addition, the usual properties of addition still apply, but a couple of the important ones look a little different. {{CMD_125}} {{CMD_126}} {{MATH_127}} {{CMD_128}} {{MATH_129}} {{CMD_130}} {{CMD_131}} Find the value of the sum: {{MATH_132}} {{CMD_133}} First, we'll use the properties above to split this into two sums, then factor the {{MATH_134}} out of the first sum. {{ENV_135}} The two sums we have left, can be found using formulas 1 and 3 above! We see that: {{MATH_136}} Similarly: {{MATH_137}} Putting all that together, {{MATH_138}}. {{CMD_139}} {{CMD_140}}