SOLUTION: If an= 27 , a1= -12 and d=3 find n

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Question 1154461: If an= 27 , a1= -12 and d=3 find n
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39618)   (Show Source): You can put this solution on YOUR website!
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If an= 27 , a1= -12 and d=3 find n
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You are given .
Just substitute and solve.
Answer by ikleyn(52794)   (Show Source): You can put this solution on YOUR website!
.

In arithmetic progression


     =  + (n-1)*d.


In your case, it takes the form


    27 = -12 + (n-1)*3.


From this equation


    n-1 =  =  = 13.


Hence,  n = 13 + 1 = 14.    ANSWER

Solved.

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    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions
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