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What is a formula for the nth term of the given sequence? 12, 20, 28... 12,20,28...

User Kelly
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2 Answers

2 votes
The formula would be

8n+4

Since the increase from one term to the other is 8 the coefficient of n is 8. Subtract 8 (8*1) from 12 to get 0th value (4).
User Hfisch
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the formula equation in multiplier-intercept form would be t(n) = 8n + 4
i found the multiplier by examining the numbers, first decide if the numbers are increasing and decreasing. for instance, in this case, they happen to be increasing value. next, you want to see what they are INCREASING by (at least in this case). you can find this by subtracting 12 from 20 which would give you 8. however, formulas aren’t always arithmetic (arithmetic means the sequence adds or subtracts), they can also be geometric, so you can’t always do that, but in this case it works. now that you have found the multiplier, which is 8, you can now find the y-intercept. you can find the y-intercept by subtracting 8 from 12 which gives you 4. this is the 0th term. therefore, the equation would be t(n) = 8n + 4.
User Tom Miller
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