frompariswithxoxo
contestada

Which of the following functions describes the sequence 4, –2, 1, –12, 14, . . .? A. f(1) = 4, f(n + 1) = –2f(n) for n ≥ 1 B. f(1) = 4, f(n + 1) = f(n) – 2 for n ≥ 1 C. f(1) = 4, f(n) = 12f(n + 1) for n > 1 D. f(1) = 4, f(n) = –12f(n – 1) for n > 1

Respuesta :

JeanaShupp

Answer: D. [tex] f(1) = 4,\ \ f(n+1)=\dfrac{-1}{2}f(n) [/tex]

Step-by-step explanation:

The given sequence:  [tex]4, -2,1,\dfrac{-1}{2},\dfrac14,....[/tex]

Here, first term: [tex]f(1)=4[/tex]

Second term: [tex]f(2)=-2[/tex]

Third term : [tex]f(3)=\dfrac{-1}{2}[/tex]

It can be observed that it is neither increasing nor decreasing sequence but having the common ratio.

Common ratio: [tex]r=\dfrac{f(2)}{f(1)}=\dfrac{-2}{4}=\dfrac{-1}{2}[/tex]

So, [tex]f(n+1)=\dfrac{-1}{2}f(n)[/tex]  [as in G.P. nth term= [tex]a_{n+1}=ar^n[/tex]]

Hence, correct option is D. [tex] f(1) = 4,\ \ f(n+1)=\dfrac{-1}{2}f(n) [/tex]

Otras preguntas