In the six-term sequence A, B, C, D, E, F, each term after the first three is the sum of the previous three terms.

If D = 15 and E = 24, determine the value of A.

Solution to the Problem:

Here is the solution:

A = 6.

E = D + C + B
D = A + B + C

24 = 15 + B + C
15 = A + B + C

9 = 15 - A
so A = 6


Correctly solved by:

1. Colin (Yowie) Bowey Beechworth, Victoria, Australia
2. Davit Banana Istanbul, Turkey
3. Dr. Hari Kishan D.N. College,
Meerut, Uttar Pradesh, India
4. Seth Cohen Concord, New Hampshire, USA
5. Mrs. Painter's Honors Precalculus Class Broome High School,
Spartanburg, South Carolina, USA