Answer:
f(x) = 80(1/4 x^x-1) ⇒ first answer
Step-by-step explanation:
* Lets explain the geometric sequence
- In the geometric progression there is a constant ratio between
each two consecutive numbers
Ex:
5 , 10 , 20 , 40 , 80 , ………………………. (×2)
5000 , 1000 , 200 , 40 , …………………………(÷5)
* General term (nth term) of a Geometric Progression:
- U1 = a , U2 = ar , U3 = ar2 , U4 = ar3 , U5 = ar4
∴ Un = a(r)^n-1, where a is the first term , r is the constant ratio
between each two consecutive terms and n is the position of
the number in the sequence
* In the problem we have 4 answers we will search which one can
be put in the form a(r)^n-1
- The first answer is 80(1/4 r^x-1)
∵ We can multiply 80 by 1/4 ⇒ 80 × 1/4 = 20
∴ It will be 20(x^x-1) ⇒ the form of the geometric sequence
* The answer is the first answer
