Answer:
a. Geometric
b. 20, 10 and 5
c. Tn = 20(0.5)^n-1
d. 0.00004 ft
Explanation:
a. The sequence is geometric
The reason for this is that we will be multiplying each term by a particular value
If it was arithmetic, we would have been adding instead. But since it is geometric, we shall multiply terms by a particular number
b. 1st term is
20
second term
1/2 * 20 = 10
Third term
1/2 * 10 = 5
c. Explicit formula
Mathematically, that will be;
Tn = ar^n-1
Where r is 1/2 or 0.5
Tn = a(0.5)^n-1
where Tn is the present term and n is the present number of the term
d. 20th term
T20 = 20 * 0.5^19
T20 = 0.00004 ft