Adapted from SCSU Math Contest

Algebra Level 3

Suppose that F ( 1 ) = 2 F(1)=2 and F ( n + 1 ) = 2 F ( n ) + 1 2 F(n+1)=\dfrac{2F(n)+1}{2} for n = 1 , 2 , 3.... n=1,2,3.... Determine the value of F ( 2017 ) F(2017) .


The answer is 1010.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Zach Abueg
May 29, 2017

F ( n + 1 ) = 2 F ( n ) + 1 2 = F ( n ) + 1 2 \displaystyle F(n + 1) = \frac{2F(n) + 1}{2} = F(n) + \frac 12

This is simply an arithmetic sequence with d = 1 2 d = \frac 12 and a 1 = 2 a_1 = 2 .

a 2017 = 2 + 1 2 ( 2016 ) a n = a 1 + d ( n 1 ) = 1010 \begin{aligned} \displaystyle a_{2017} & = 2 + \frac 12(2016) & \small \color{#3D99F6} a_n = a_1 + d(n - 1) \\ & = 1010 \end{aligned}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...