We are given the following sequence

Let us find a general formula for this sequence.
Recall that the geometric sequence is given by

Where aₙ is the nth term, a₁ is the first term and r is the common ratio
The common ratio is basically the ratio between any two consecutive terms

So, the common ratio is -5
The first term of the sequence is -3
So, the general formula for the given sequence becomes

Now, let us find the 8th term of this sequence
Substitute n = 8 into the above formula

Therefore, the 8th term of the sequence is 234375