Given this equation:
$f_{2k}2^{2k}u_{2n-2k}2^{2n-2k}$=$f_{2k}u_{2n-2k}2^{2n}$
then it asks to "sum over k" to obtain this equation:
$u_{2n}2^{2n}$=$f_0u_{2n}2^{2n}+f_2u_{2n-2} 2^{2n}$+....+$f_{2n}u_02^{2n}$
then dividing both sides of the equation by $2^{2n}$ completes the proof I need.
My question is, what does it mean by "sum over k"
Does it want me to sum from 0 to $\infty$ for k? And which k, all of them? And how? Do I start by plugging in o to all k's and see what happens? continue then add them all up? Seems strange to me! Any help will be greatly appreciated!
Obviously, summing from $k=0$ to $k=n$.