anonymous one year ago is double sum defined as ∑∑ a(i,j) = ∑ (∑a(i,j))

1. Empty

Yep, but since addition is associative and commutative you can interchange summing on i or j if you want.

2. anonymous

huhm... ok. If we have ∑ a(i), what is a(i) called?

3. Empty

It's a term in the summation, it's essentially a function of i, so for example: $\sum_{i=1}^3 a_i = a_1+a_2+a_3$ Suppose that $$a_i = 7i^2$$ then we could write: $\sum_{i=1}^3 7i^2 = 7*1^2+7*2^2+7*3^2=98$

4. anonymous

It's called the "summand" honey

5. anonymous

cool