# Summation Rules

n
∑ 3
k=0

How does this make sense when k=0?

The sum is ##3+3+...=3(n+1)##

The sum is ##3+3+...=3(n+1)##
Oh okay. The lower bound is the index origin and doesn't matter if it is negative?
n
∑ 3
k=-1
3+3+...=3(n+2)

Correct!

DrClaude
Mentor
To summarise,
$$\sum_{k=a}^{b} c = c (b-a+1)$$
for constant ##c##.

jbriggs444
$$\sum_{k=a}^{b} c = c (b-a+1)$$