answer to 1:-

let the progression is given by where is the common ratio and is the first term and the progression possesses terms.

let us take th term from the beginning and end, respectively. the terms are then given by and (ie, th term from the beginning). so their product is given by ie .

also, the product of the first and last terms of the progression is .

hence the result.

try the second one yourself. best of luck.