Pre college algebra

fishman13

fishman13

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Who knows how to write out and use recursive equations. Thbats the uniot we are in right now and I dont understand. Ex. 10,5,0,-1
Wright a recursion formula for this system of numbers?
 
FishInMaryland

FishInMaryland

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fishman13 said:
Who knows how to write out and use recursive equations. Thbats the uniot we are in right now and I dont understand. Ex. 10,5,0,-1
Wright a recursion formula for this system of numbers?
Click to expand...

Is that really the sequence of numbers you were given, or should it be 10, 5, 0, -5?

If those really were the right numbers, what did the answer turn out to be?
 
FishInMaryland

FishInMaryland

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I'm a little late responding, but by now hopefully you learned that you have to figure out the pattern in the numbers, then come up with a formula for the next number in the sequence, based on the prior number. So, for this one, you subtract 5 from the previous number in the sequence. You know that "n" means the nth number in the sequence, so the (n-1)th number is the immediately preceding number?

Formula for your example is Tn = T(n-1) -5

The n and (n-1) above should be subscript, but I can't do that in this editor.
 
turfboss

turfboss

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I can't figure out the answer for the nth term in the sequence given above - if the T(n) I am looking for is the 20th term in this sequence the formula given requires me to know what the 19th number in the sequence is before I can figure out the 20th term. In general, the nth term of an arithmetic sequence is given by the formula
a(n) = a(1) + (n-1)d where n is the nth term you are looking for and a(1) is the first term in the sequence and d is the difference between the numbers in the given sequence. So for 10,5,0,-5 the first number in the sequence a(1) is 10, you are looking for the next number in the squence which in this case is the 5th number so (n-1) is 4 and the d = -5 so [10 - 4*(-5)] is 10 - 20 = -10. This formula works for geometric and arithmetic sequences but Cameron was asked to write a recursive formula for this sequence and this formulation is not a recursive formula. It will give you the nth term in a simple geometric progression but would not for example provide the answer he is looking for when the difference is not a simple integer.

This is College Algebra (not arithmetic) and "recursive" formulations require calculating the smaller differences in numbers in a sequence and using the difference between them in such a manner as to build the summation series for enough of the first elements to be able to calculate future differences - a really good example (of how to calculate a Fibonacci Series) for those who are interested (and hopefully Cameron is) can be found at the following link - http://www.cs.uiuc.edu/~mfleck/building-blocks/version-1.0/recursive-definition.pdf
 
Beeman

Beeman

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WTF!!! If I have 12 donuts, and I eat one, I have 11 left! What more do I need to know?!?! I was a math/science major in high school and college. I have NEVER needed to use algebra or calculus EVER since! And I still have 11 donuts! What I have learned thru this long, but tenuous life we all lead, is that I have donuts to share with all sentient beings(although they're starting to 'firm up'!) Amen
 
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