Question

sequence and series examples​

Answer 1

Given the sequence An = {1, 3, 5, 7, 9},

(a) what is the value of a3?

(b) Find the value of \mathbf{\color{green}{\displaystyle{\sum_{\mathit{n}=1}^5\,\mathit{a}_{\mathit{n}}}}}  

n=1

∑

5

​  

a  

n

​  

 

 

MathHelp.com

Need a personal math teacher?

(a) The index of a3 is n = 3 so they're asking me for the third term, which is "5".

(b) The funky symbol is the Greek capital letter "sigma", indicating a series. That means that they're asking me here to do the addition of the terms of the sequence. The "value" they're asking me to find is the total, the sum, of all the terms an from a1 to a5; in other words:

a1 + a2 + a3 + a4 + a5

= 1 + 3 + 5 + 7 + 9 = 25

Then my answers are:

value of a3: 5

value of sum: 25