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Do you have to plug in numbers to make a sequence that is greater than 2?

 Apr 17, 2019
 #1
avatar+111433 
+3

2 or greater

 

a.  The formula  is   an =    an-1 - 3....so   a2 = a2-1 - 3  =  a1 - 3

Notice GM  that we are just subtacting 3 from the previous term to get the next....and the first term is 7...so

7, 4, 1 , -2

This is arithmetic

 

 

b.  The formula  is  bn = 2bn-1  - 1   .....so    b2 = 2b(2-1) - 1  =  2b1 - 1

We are taking  twice the previous term and subtracting 1 to get the next term and the first term is  2

So we have

2, 3, 5, 9

This is neither

 

c. The formula is  cn  = 10cn-1   ...  so.....c2  = 10 c(2 - 1)  = 10c1

So....we are just taking 10 times the previous term to h=get the next 

So      3, 30, 300, 3000

geometric

 

d.   A little tricky.....

We have

 dn  = n * dn-1   .....  first term is  1

Second term...n = 2      

d2 = 2 * dn-1   =    2 * d(2 - 1)  =  2 * d1  = 2 * 1  =  2

d3  =   3* d2  =  3 * 2  = 6

d4  = 4 * d3  = 4 * 6 = 24

 

So we have

 

1, 2, 6 , 24

neither......no common difference or common ratio

 

 

 

cool cool cool

 Apr 17, 2019

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