in an arithmetics sequence the 17th term is 6 less than 3 times the 1st term. Find the first three terms
a+16d = 3a-6
a = 8d+3
So, pick d and you have a:
d=1, a=11
11,12,13,...,27
27 = 3*11-6
d=0, a=3
3,3,3,...,3
3 = 3*3-6
As you can see, any value of d will work.