Question

If an =5-11n, then find the common difference

Answer 1

d=an-an-1
d=5-11n-5+11(n-1)
d=-11

Answer 2

a1 = 5-11x1 = -6
a2 = 5-11x2 = -17
d = a2-a1 = -17-(-6) = -11