Question

difference equations?

Answer 1

amistre...hi

Answer 2

Step 1: What you want to do is drop the constant, the same as simply making
the constant zero to get the homogeneous difference equation. Then you get
a general solution to that homogenous difference equation.

Step 2: Then go back and come up with a trial solution to the non-homogenous
difference equation, the style of the trial solution being based on the kind
of terms that are creating the non-homogeneous part (this will probably be
the hardest part, so read that section of material carefully). Then put in
particular values that you know solve the difference equation, specific
values you got from working with the difference equation such as what xo
is, what x1 is, allowing you to determine what the constants in your trial
solution need to be. This gives you your particular solution.

Step 3: As the last step you combine your general solution and your
particular solution to get your complete solution for this specific
problems, and of course verify that when applied it creates the correct
values for x0, x1, .... xn.

Overall you will have started with a "difference equation" expressing how to
get x n+1 if you know x n, and you are ending with a formula that will
calculate any x n by just knowing n. The formula allows you to calculate
any x n term without working out all of the terms ahead of it.

Answer 3

isnt this from yesterday :)

Answer 4

yes need clear understanding for solutions starting with 2b

Answer 5

I have 0,0 1, -1 2, -1.5 , 3 -1.75 4 -1.875, 5 -1.9375 6, -1.96875 for a

Answer 6

this is on 2a right?

Answer 7

yes

Answer 8

you need to track these as community service hours ; )

Answer 9

add to resume

Answer 10

lol.... the problem or this session ;)

Answer 11

all of your time in OS

Answer 12

lol

Answer 13

just realized that was a joke, lol

Answer 14

homo diff is dropping the constant... :)

Answer 15

what does dropping the constant do for us?

Answer 16

gives us xsubn?

Answer 17

the good computers are all locked away today; this one hates openstudy. small font, no formating..... just awful

Answer 18

might go to McDs later and use the wifi.... if it aint busy/closed

Answer 19

yeah my laptop will not let me do anything in os anymore so have to sit at desktop

Answer 20

are you in school

Answer 21

so if we strip the constant; we are just left with:

Xn+1 = (1/2)Xn which always equals itself, so I dont quite know why wed do that....

Answer 22

yeah, in the computer lab downstairs....

Answer 23

are you a student

Answer 24

yup

Answer 25

me to and unemployed since move

Answer 26

taught 8th grade Algebra back in SC

Answer 27

i cant get work since I hurt my back.

Answer 28

ima "liability"

Answer 29

oh no sorry to hear that...ever thought about starting online tutoring business..I can help you out

Answer 30

i thought about trying to do something like that; id be nice to have some sort of income other than PELL grant...

Answer 31

I'm studying off loans for now ; ( that is why I have to take this extra module that has nothing to do with my program of study...technically

Answer 32

send me your email address and I can send you a presentation I'm actually presenting on Tues. and the link to my website...I just started in March and have
3 students now but hope to advertise some more this summer...brishundra@yahoo.com

Answer 33

So the complete solution is jsut finding an equation that will sum up all the nth terms....

Answer 34

I have xn=(0.5)raised to n *C

Answer 35

keep looking back at table in a and messing me up bc different ?

Answer 36

couldnt we just solve for "Xn" and plug it in? maybe?...

Answer 37

y = .5(0) - 1 + .5(1) - 1 +.5(2)-1 + .5(3) -1 seems to be what they are getting at.

Answer 38

we can rearrange our equation to see it better:

y - .5(0) + .5(1) + .5(n) - 1 - 1 - 1 - 1

Answer 39

we need ".5(n)" for any given interation of n right?

Answer 40

yes

Answer 41

and we need -(1n) for every iteration of n right?

Answer 42

whatis:

.5(n) - (n) = ?

Answer 43

the constant

Answer 44

at =1 we get -1.5 right?

Answer 45

at n=2 we get:

.5(2) - (2) = -2.5 right?

Answer 46

-1.5 maybe, gonna have to see this on a calculator.... terrible font

Answer 47

ok

Answer 48

whats yout table in a look like?

Answer 49

0,0 1, -1, 2, -1.5 3, -1.75...

Answer 50

4 -1.875 5 -1.9375 6 -1.96875

Answer 51

i get from teh original stuff, not my stuff:

0; -1; -1.5; -1.75; -1.875...

Answer 52

I had that when I first started this , lol

Answer 53

but looked at xo=0 and thought I was wrong

Answer 54

your "key returns" arent formating; they look like this:

Answer 55

the value of X0 = 0 then it iterates from there

Answer 56

ok so 6 -1.984375

Answer 57

we get add ons of 1/2; 3/4; 7/8; 15/16; 31/32; 63/64; 127/128; 511/512

Answer 58

(2^n)-1
------
2^n

Answer 59

[(2^n)-1]
-1 - -------- = y
2^n

Answer 60

thats our formula/equation for this bit lol

Answer 61

n=[1,inf]

Answer 62

it fits right?

Answer 63

the bottom of the fractions ar plugging away at 2^n; and the tops are following one step behind at (2^n)-1

Answer 64

X{n+1} = (1/2) X{n}

2X{x+1} = X{n} I got no idea how they supposed to do this and come up with that lol

Answer 65

X{n+1} 1
----- = ---
X{n} 2 <-- 2^n ? if we borrow that "n"

Answer 66

any ideas?

Answer 67

lost...trying something

Answer 68

I got the right equation; just dont know how to get it from their stuff....

Answer 69

is that for c

Answer 70

thats for ..... D i think

Answer 71

you got a link to the "look over this material" part of it?

Answer 72

The style of the trial solution being based on the kind of terms that are creating the non-homogeneous part (this will probably be the hardest part, so read that section of material carefully).

Answer 73

got 10 minutes til the college closes....

Answer 74

and StLeo is a catholic college so that ones closed for today as well; my internets are getting scarce :)

Answer 75

email me the "material" section: tony031172@gmail.com

Answer 76

ok THANKS a bunch!

Answer 77

http://www.aw-bc.com/ggts/