+0  
 
-5
142
1
avatar+60 

How do I get these rules from the sequences?

 Apr 17, 2019
 #1
avatar+106519 
+2

a.  This looks to be arithmetic.....common difference between terms =2

And the first term = 2

So

an  = 2 + 2(n - 1)   which we can simplify as   an = 2n

 

b. Also arithmetic .....common difference = 2 ....first term = 3

 

an  = 3 + 2(n - 1)     which we can simplify as   an  = 2n + 1

 

c. Arithmetic....common difference = -25  and the first term is 50

 

an  = 50 - 25(n - 1)    =   75 - 25n  

 

4. Geometric.....common ratio  = 1 / (1/3)  = 3....first term = 1/3

 

an  = (1/3)*3^(n - 1)

 

 

cool cool cool

 Apr 17, 2019

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