Proof: Since the equation (3) has two distinct roots, the sequence
, = c1(r1)n + c2(r2)n (5)
is the solution of the equation (1). Giving to n the values n = 0 and n = 1 and
solving this system of linear equations, we obtain a unique value for c1 and c2. So,
we get the following distinct values, c1 =
√ and c2 =
√ = c1.
Since 2√1 , we can express c1 and c2, respectively by c1 =
and c2 =
. Now, using (5), we obtain (4) as required.
∎