September 22nd, 2015, 08:44 PM  #1 
Newbie Joined: Oct 2011 Posts: 6 Thanks: 0  Second order difference equation
Sorry, need help to solve this urgently

September 22nd, 2015, 10:06 PM  #2 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,671 Thanks: 2651 Math Focus: Mainly analysis and algebra 
Without any knowledge of Mathcad, I suspect you want a loop structure to repeatedly calculate values using that formula until you hit $L_43$. It is possible to solve the sequence exactly for all $n$ quicker than I could write something in Mathcad, but since this is presumably a problem to get you familiar with the software, I'd do it that way. 
September 23rd, 2015, 12:39 AM  #3  
Newbie Joined: Oct 2011 Posts: 6 Thanks: 0  Quote:
 
September 23rd, 2015, 03:25 AM  #4 
Senior Member Joined: Dec 2013 From: some subspace Posts: 212 Thanks: 72 Math Focus: real analysis, vector analysis, numerical analysis, discrete mathematics 
For $\displaystyle n = 3:$ $\displaystyle L_3 = 2L_2  \tfrac{3}{2}L_1 = 2 \cdot \tfrac{1}{5}  \tfrac{3}{2} \cdot \tfrac{1}{10} = \tfrac{1}{10}$ Repeat until $\displaystyle n = 43$. 
September 23rd, 2015, 05:03 AM  #5 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,671 Thanks: 2651 Math Focus: Mainly analysis and algebra 
How about if I solve a different but similar problem and you apply the method to this one? Let $\displaystyle 8a_n = 2a_{n1} + 3a_{n2} \qquad a_0 = 0, \; a_1 = 1$ 
September 23rd, 2015, 06:22 AM  #6 
Newbie Joined: Oct 2011 Posts: 6 Thanks: 0  
September 23rd, 2015, 06:23 AM  #7  
Newbie Joined: Oct 2011 Posts: 6 Thanks: 0  Quote:
 
September 23rd, 2015, 06:49 AM  #8 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,671 Thanks: 2651 Math Focus: Mainly analysis and algebra 
What do you not understand in the example I gave? This site is not intended as a place where you come to get your homework done for you. In the example I gave, we'd put $\displaystyle n = 43$ into the final equation to get $\displaystyle a_43$. 
September 23rd, 2015, 09:24 PM  #9  
Newbie Joined: Oct 2011 Posts: 6 Thanks: 0  Quote:
 
September 23rd, 2015, 11:44 PM  #10 
Newbie Joined: Oct 2011 Posts: 6 Thanks: 0  Is it correct to do in this way?


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