Question 1206934
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Find the 11th term of an arithmetic sequence whose first term is 3x + y and whose common difference is x + 2y.
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It is easy.


We are given an AP with the first term  {{{a[1]}}} = 3x+y  and  common difference d = x+2y.


The  11-th term is  {{{a[1]}}} + d*(11-1) = (3x+y) + 10*(x+2y) = 3x+y + 10x+20y = 13x + 21y.


<U>ANSWER</U>.  The 11-th term of the AP is  13x+21y.
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Solved.