Since Lk = Lk−1 + Lk−2, we first obtain Lk+7 = Lk+6 + Lk+5 on the left hand side of the above equality, and for on the right
hand side of the equality, we can write Lk+5 = Lk+4 +Lk+3. Hence, by iterating this procedure, we can write Lk+1 = Lk +Lk−1.
Therefore