Question

The recursive formula for an arithmetic sequence is an = an - 1 + d.

Answer 1

A) -5 should be your answer

Answer 2

If an is a5
and
an-1 is a4

then using your recursive formula for an arithmetic sequence
an=an-1 +d
then
a5=a4+d

now, a4 =6 and common difference "d"  is d=-11
hence
a5=6 -11
6-11= -5


any questions?