# Summation question

by joshmccraney
Tags: summation
 P: 346 hey pf! can someone explain to me what to do if presented with an equation like this: $$\sum_{i=1}^{n}A_i=i$$ is this identical to stating $A_i=i$? either way, can you please explain. thanks! josh
 Quote by joshmccraney hey pf! can someone explain to me what to do if presented with an equation like this: $$\sum_{i=1}^{n}A_i=i$$ is this identical to stating $A_i=i$? either way, can you please explain. thanks! josh
 Engineering Sci Advisor HW Helper Thanks P: 7,172 Just taking it at face value, it means ##A_1 + A_2 + \cdots + A_n = i## The ##i## in the sum is a "bound variable" or "dummy variable". You could replace it by anything else (except ##n##) without changing the meaning. The ##i## on the right hand side means ##i##. But using ##i## twice in one equation like that is horrible, as Mark44 said. It would have been more literate to write something like $$\sum_{k=1}^n A_k = i$$