MHB 13.3.2 What is the 50th term of the sequence

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The 3rd and 4th terms of an arithmetic sequence are 13 and 18, indicating a common difference of 5. The general term of the sequence is derived as a_n = 3 + (n-1)5. Calculating the 50th term using this formula results in 248, not 250 as previously suggested. The discussion highlights confusion regarding the correct formula for the nth term in an arithmetic sequence. The correct answer for the 50th term is 248.
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The 3rd and 4th terms of an arithmetic sequence are 13 and 18. respectively.
What is the 50th term of the sequence!
a, 248 b. 250 c. 253 d, 258 e, 763

b the common difference is 5 so $5\cdot 50=\boxed{250}$

basically these are easy but I still seem to miss the goal posts
 
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Okay, so d = 5. What is the first term in the series? What is the equation to get the nth term of the series?

-Dan
 
Since this has been here a while and, as topsquark implied, Karush's answer is wrong:
An "arithmetic sequence" has the form a, a+ r, a+ 2r, a+ 3r, a+ 4r ..., with "common difference" between two successive terms r. The general term is "a+ (n-1)r", NOT "nr".

Here two successive terms are 13 and 18 so the "common difference" is 18- 13= 5 as Karush said. But 13= 3+ 2(5) and 18= 3+ 3(5) so the general term is $a_n= 3+ (n-1)5$ and the 50th term is 3+ 49(5)= 248, not 250.
 
Mahalo
yeah that post kinda got left hanging
i never found these essy
 
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