Three distinct integers satisfy the following three conditions :
What is the value of ?
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Let the integers be a , b = a + d , c = a + 2 d (since they form an AP). Since a b c = 1 7 9 5 5 ⟹ a ( a + d ) ( a + 2 d ) = 1 7 9 5 5 . . . ( 1 )
( 3 a + b ) , ( 3 b + c ) , ( 3 c + a ) form a geometric sequence ⟹ ( 3 b + c ) 2 = ( 3 a + b ) ( 3 c + a ) ⟹ ( 4 a + 5 d ) 2 = ( 4 a + d ) ( 4 a + 6 d )
⟹ 1 9 d 2 + 1 2 a d = 0 ⟹ a = 1 2 − 1 9 d Substituting in ( 1 ) we get:
1 2 1 9 d ⋅ 1 2 7 d ⋅ 1 2 5 d = 1 7 9 5 5 = 3 3 ⋅ 1 9 ⋅ 7 ⋅ 5
⟹ d = 3 6 ⟹ a = 1 2 − 1 9 d = − 5 7
The sum of these terms is: a + b + c = 3 a + 3 d = 3 ( 3 6 + ( − 5 7 ) ) = − 6 3