I have attached a photograph of my problem to save time on typing the question

I have done the first part to obtain the expression for equilibrium bond length and in the second part I solved that equation for A and substituted it into my binding energy equation and obtained an answer with the order of magnitude to the -60 so when I square it in my calculator I get 0, I’m assuming this is incorrect somehow although I don’t see what I have done wrong

Thanks for any help in advanced, all necessary equations are present in the problem

http://ift.tt/1p6I8yW