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There was one example in my school work today that didn't make sense.

You need to figure out the formula for the following pattern

-1, 5, -9, 13, -7

 

The provided solution is:

Odd numbers: -1^n

Even numbers: 4n -3

 

They don't show how they got there at all.

 

As you could probably see the odd number solution does not work.

But I can't figure out the actual formula.

Could someone please help me with this?

Guest Mar 5, 2018
edited by Guest  Mar 5, 2018
 #1
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The formula is a combination of both ie (-1)n (4n-3)  where n = 1,2,3,....

 

you see the (-1)is just the mathematical way of putting a minus sign in front of a number.

 

odd powers give a minus and even powers give a plus eg (-1)= -1 ,  (-1)= 1

 

and of course the 4n-3 gives you  1,5,9,......

Guest Mar 6, 2018
 #2
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Your suggestion will work only if the 5th term (-7) is wrong, which is quite likely because -17, which will work, is very close to -7 that he/she has written down.

Guest Mar 6, 2018

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