Triple Sequence

https://open.appacademy.io/learn/full-stack-online/intro-to-programming/triple-sequence

def triple_sequence(start, length)
final = []
i = 1
num = start
final << num

while i < length
	num *= 3
	final << num
	i += 1
end

return final
end

print triple_sequence(2, 4) # => [2, 6, 18, 54]
puts
print triple_sequence(4, 5) # => [4, 12, 36, 108, 324]
puts

While I get the same right answers, am I following the instructions properly? It seems my code is simpler but am I learning the process to come to the right conclusion? Should the instructions be more specific to do this problem in a certain way to learn the fundamentals better?