In mathematics, ageometric progression, also known as ageometric sequence, is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed non-zero number called thecommon ratio. For example, the sequence 2, 6, 18, 54, ... is a geometric progression with common ratio 3. Similarly 10, 5, 2.5, 1.25, ... is a geometric sequence with common ratio 1/2. The sum of the terms of a geometric progression is known as ageometric series.

Thus, the general form of a geometric sequence is

and that of a geometric series is

wherer ≠ 0 is the common ratio anda is a scale factor, equal to the sequence's start value. - Wikipedia.

A) -16,-8,-4,-2,-1

to find common ratio, divide your second term by the first term. or divide your third term by your second term and so on..

thus, r = -8/-16 = -4/-8 = -2/-4 = -1/-2 =1/2.

now that you have your common ratiorand your first terma,

the formula for geometric progression is

now your a=-16 and r=1/2

so the expression for the general term for this geometric progression is

= -16[(1/2)^(n-1)]

same goes for question b c and d..and question 2 too!