Consider an arithmetic which has the second term equal to 8 and the fifth term equal to 10

2 answers

hmmm -- ver-r-r-ry nice!
a + d = 8
a + 4 d = 10
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0 - 3 d = -2
d = 2/3
a = 8 -2/3 = = 7 1/3 = 22/3
so
Tn = 22/3 + (n-1)* 2/3