Use summation notation to write the series 2.2 + 8.8 + 15.4 + .... for 5 terms

Note: In each of these images, the lower limit of the summation notation is either "n = 1" or "n = 0".

4
∑(-5.4+6.6n)
n=0

4
∑(-4.4+6.6n)
n=0

5
∑(-6.6+4.4n)
n=1

5
∑(-4.4+6.6n)
n=1