This question was recently asked and was asking "Can someone poke a hole in my work for me please so I can realise my error?" which was promptly answered with an answer that pointed out the error in the OP's attempt and fixed it.
It then also received another answer providing an alternative approach to solving the problem and was accepted.
Jik then comments:
The question was "Is this right?" and "Can someone poke a hole in my work for me please so I can realise my error?" While this technically answers the question by giving the right answer, this doesn't seem like a good answer to the question.
To which quasi responds:
The hole was already identified in another answer. More important for the OP is to see a better way (so that in future problems, the OP can benefit from an awareness of the option shown in my answer).
Is it acceptable etiquette to provide alternative solutions to a proof verification question after the proof verification has been covered in another answer?