With a = 8 b = 25 and c = c
there will be two real roots when b2 - 4ac > 0.
b2 - 4ac > 0 ---> 252 - 4·8·c > 0 ---> 625 - 32c > 0
-32c > - 625
c < 625/32 = 19.53 (approx)
All integers in the range 1, 2, 3, ..., 17, 17, 19 will work.
Find their product ...