December 26th, 2017, 03:14 PM  #11 
Senior Member Joined: May 2016 From: USA Posts: 1,148 Thanks: 479 
I am late to this thread but $\displaystyle \sum_{j=k}^n \text { expression in j and n }$ means to loop through, incrementing j by 1 each time, starting with j = k and ending with j = n, to calculate the value of the expression in each iteration of the loop, and to add that value to a cumulative sum. $\displaystyle \sum_{j=2}^5 nj^2$ is computed as follows Initialize sum = 0 First iteration j = 2 so $nj^2 = 5 * 2^2 = 20 \text { and } 0 + 20 = 20.$ Second iteration j = 3 so $nj^2 = 5 * 3^2 = 45 \text { and } 45 + 20 = 65.$ Third iteration j = 4 so $nj^2 = 5 * 4^2 = 80 \text { and } 80 + 65 = 145. $ Last iteration j = 5 so $nj^2 = 5 * 5^2 = 125 \text { and } 125 + 145 = 270.$ Summation notation is a highly abbreviated way to explain a procedure. Nothing fancy about it. 
December 28th, 2017, 03:32 PM  #12  
Newbie Joined: Feb 2012 From: Central Florida Posts: 10 Thanks: 0  Quote:
Last edited by skipjack; December 28th, 2017 at 04:02 PM.  
December 28th, 2017, 04:07 PM  #13 
Global Moderator Joined: Dec 2006 Posts: 19,724 Thanks: 1807 
Some calculators may be more flexible than others as to how a summation is entered.


Tags 
function, inverse, question 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Inverse function of a differentiable function  WWRtelescoping  Calculus  2  September 2nd, 2014 04:57 AM 
Find all linear function given a function equals its inverse  deSitter  Algebra  4  April 10th, 2013 01:17 PM 
Inverse trigonometric function question  razzatazz  Trigonometry  12  March 5th, 2013 11:08 PM 
Inverse of a continuous function is continuoust, a question  annakar  Calculus  3  January 11th, 2013 06:07 AM 
find inverse of inverse function  jaredbeach  Algebra  1  November 17th, 2011 11:58 AM 