HELP PLEASE AAAAAAAAAAA

  last choice

In general if we have first term a[1] and common difference d, such that

a[n] = a[n-1] + d

then the explicit formula is

a[n] = a[1] + d(n-1)

First choice has d=-4 so needs a minus sign in the explicit formula.

Second choice has a=-100 so needs a negative sign for the 100.

Third choice swaps a[1] and d, oops.

-0.25. You basically divide 1 by 4 and you will get the decimal form. Also you add the negative