The sum of three consecutive terms of a series are a, a + d and a + 2d.
Their sum is 15, a + a + d + a + 2d = 15
=> 3a + 3d = 15
=> a + d = 5
=> a = 5 - d
The product of the same three terms is 45
a*(a + d)*(a + 2d) = 45
=> (5 - d)*5*(5 - d + 2d) = 45
=> 5*(5 - d)(5 + d) = 45
=> 5*(25 - d^2) = 45
=> 125 - 5d^2 = 45.
=>5d^2 = 80
=> d^2 = 16
=> d = 4 or d = -4
With d = 4, a = 1
The terms of the series have a common difference of 4 and one of the terms is 1.
With d = -4, a = 9
The terms of the series have a common difference of -4 and one of the terms is 9
Two arithmetic series satisfy the given conditions, one has a common difference of 4 and one of the terms is 1 and the other has a common difference of -4 and one of the terms is 9.
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