78125 = -5^7
So, starting with 5^-2, the 10th term is -5^7
Note that the 3rd term is 1=5^0.
So, you have to multiply by -5 another 7 times to get to -5^7.
Determine the number of terms in the geometric ssequence: 1/25, -1/5, 1, -5,...., -78125
i get n=8 is this correct
1 answer