Anonymous

terms of an AS: a, a+2d, a+8d sum is 78 3a + 10d = 78 terms of a GS: a+2d = ar a+8d = r(a+2d) = ar+2dr 6d = 2dr d = 0 or r = 3 d = 0, a = 26, r = 1 26, 26, 26 r = 3 a+3a+9a = 78 13a = 78 a = 6 6, 18, 54

Anonymous

The sum of 3 numbers is 78. They form a geometric sequence, and can be the first, third, and ninth term of an arithmetic sequence. a + (a + 2d) + (a + 8d) = 78 3a + 10d = 78 a + ar + ar^2 = 78 Integer solutions: a = 6, d = 6, r = 3