maths sequences help

I'm in the process of completing my homework and I am struggling to do some of the questions.

- find the 50th term of the following sequences:

1. 5, 5√5,25,25√5

2. 4a,4,4/a,4/a^2

Any help and explanations would be appreciated

1. Common ratio is $\sqrt{5}$

2. Common ratio is $\frac{1}{a}$

and work from there using your sequence formulae. Just divide $u_{n+1}$ by $u_n$ and similarly down the line in order to be sure that these are indeed common ratios.

Thank you, and is that the formula for finding the 50th term or the formula for checking the common ratio?

Think about it. Why would it for the 50th term?? If you divide a term by the one right before it you will get the ratio between the two.

I already worked out the common ratio for both sequences. Is the formula for finding any terms an=a x r^n-1 ?