Answer:
This is cheating
Step-by-step explanation:
First you follow what your teachers tell you to do and listen
First term (a1) is -1
recursive formula goes like this

is the nth term

is the term before that
we normally have

we see each term is multipying by -3 to get next one
so that would be

where a1=-1
the 3rd option is correct except that it is the explicit formula
so answer is 2nd one
I believe the answer is 2/3n
Since 13 can only be divided evenly by 1 and 13 (itself), it is called a prime number.
Answer is A, basically using the Pythagorean theorem but in a slightly different way, should still get you the same answer.