Respuesta :

The d value is going to be -3 because you have to compute the differences of all the adjacent terms. 2-5=-3    -1-2=-3     -4-(-1)=-3   -7-(-4)=-3   The difference between all the adjacent terms is the same and equal to -3
Common difference (d) = a(2) - a(1) = 2 - 5 = -3

In short, Your Answer would be -3

Hope this helps!