SOLUTION: Next number in each pattern: (1) 3, -6, 12, 4, 20, ? (2) 7, 16, 8, 27, 9, ? (3) 2, 7, 26, 101, 400, ? (4) 7, 21, 8, 72, 9, ?

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Question 1085744: Next number in each pattern:
(1) 3, -6, 12, 4, 20, ?
(2) 7, 16, 8, 27, 9, ?
(3) 2, 7, 26, 101, 400, ?
(4) 7, 21, 8, 72, 9, ?

Answer by Edwin McCravy(20055)   (Show Source): You can put this solution on YOUR website!
 3, -6, 12, 4, 20, ? 

Start with 3    <-- get 1st term, 3
Subtract 9      <-- get 2nd term, -6
Add twice 9     <-- get 3rd term, 12
Subtract 8      <-- get 4th term, 4 
Add twice 8     <-- get 5th term, 20
Subtract 7      <-- get 6th term, 13   <-- the answer
Add twice 7     <-- get 7th term, 27
Subtract 6      <-- get 8th term, 21
Add twice 6     <-- get 9th term, 33

----------------------

(2) 7, 16, 8, 27, 9, ? 

Start with 7    <-- get 1st term, 7
Add 9           <-- get 2nd term, 16
Subtract 8      <-- get 3rd term, 8
Add 19          <-- get 4th term, 27 
Subtract 18     <-- get 5th term, 9
Add 29          <-- get 6th term, 38   <-- the answer
Subtract 28     <-- get 7th term, 10
Add 39          <-- get 8th term, 49
Subtract 38     <-- get 9th term, 11

-------------------------

(3) 2, 7, 26, 101, 400, ? 

Start with 2                           <-- get 1st term, 2
Mutiply by 4, get     8, subtract 1,   <-- get 2nd term, 7
Mutiply by 4, get    28, subtract 2,   <-- get 3rd term,  26
Mutiply by 4, get   104, subtract 3,   <-- get 4th term, 101 
Mutiply by 4, get   404, subtract 4,   <-- get 5th term, 400
Mutiply by 4, get  1600, subtract 5,   <-- get 6th term, 1595 <-- the answer
Mutiply by 4, get  6380, subtract 6,   <-- get 7th term, 6374
Mutiply by 4, get 25496, subtract 7,   <-- get 8th term, 25489 

Edwin
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