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Help on question about sequences and series watch

1. Write down the term indicated in square brackets in each of the following arithmetic progressions

81, 77, 73, ... [nth term]

I did:
a=81, d=4
nth term = a+(n-1)d
81+(n-1)4 = 81+4n-4 = 73+4n

The answer is 85-4n

So somwhere I have gone wrong with the signs.
I'm not sure where though, as far as I can see i've done it all correct, evidentely not.
2. Your "nth term = ..." bit is wrong. Surely it's just nth term = a-nd?

3. so
4. d=-4 my dear!
5. (Original post by elitespawn)
d=-4 my dear!
Got it! Why didn't I see that before? Thankyou

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