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A sequence is defined by the recursive formula f (n + 1) = f(n) – 2. If f(1) = 18, what is f(5)?

Respuesta :

Ilyes39
we have [tex]f(n+1)=f(n)-2[/tex] with [tex]f(1)=18[/tex]
so 
[tex]f(2)=f(1)-2=18-2=16,\\ f(3)=f(2)-2=14,\\ f(4)=f(3)-2=12,\\ f(5)=f(4)-2=10.[/tex]
Hence [tex]f(5)=10.[/tex]
ghanami
hello : 
this is  the arithmetic -  sequence when the common diference is : d = -2
the general term is : f(n) =f(1) +(n-1)d   .. d= -2  and f(1) =18
let : n= 5
f(5) = f(1) +(5-1)(-2)
f(5) = 18 -8 = 10

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