Arithmetic sequence for - 1 - 6 - 11 - 16 expression

hello:

note:

the nth term of an arithmetic sequence is:

An = A1 + (n-1) d ... a common difference is : d ... A1 : the first term

in this exercice : A1 = - 1 d = (-6) - ( - 1) = - 5

An = - 1 + (n - 1) (-5)

the expression is : An = - 5n + 4

That is correct u should give him brainless