We don't need any new criteria to judge that answers which just feed the question directly into CAS with no further explanation are poor quality. Even an answer which primarily relies on CAS should do more than provide the proper input and the output - what else it ought to do varies, but perhaps it should explain exactly what the functions used are doing, gesture to important bits of it, or explain how the problem can be broken into commands amenable to CAS. Sometimes "You can use CAS to solve this/aid the solution by doing _" is helpful, but there is a marked danger here: CAS is a black box. In my opinion, the best answers on this site use a lot of words beyond what is strictly necessary for the mathematics - they use extra words to clarify tricky things, offer insight into bizarre twists in proofs, or draw attention to important tricks. One of this site's strength is that it can offer strong explanations of how to resolve questions and can actually, perhaps, help people learn mathematics. Why should our site be a duplicate of this one (or various common softwares), when that one is really much better at taking suitable questions and immediately giving correct results? Correct results (even numerical) are often helpful as comments, especially on problems that seem otherwise intractable, but otherwise, it's sort of like addressing the question somewhere else. I cannot think of a reason why it would ever be helpful to something which could, with trivial effort or thought, be retrieved from computer algebra software as an answer - this is to say, answers which, like those linked to in the question above, provide only the input and output to a computer algebra system, especially when the input is not particularly cleverly composed (i.e. It, and any answer like it that favors mindlessness and I/O over understanding and exposition, should be downvoted thoroughly. I don't care if the CAS solution agrees with this somehow, either numerically or through a complicated series of identities the CAS has failed to present the answer in a useful form. In this case, as the accepted solution explains, the double integral evaluates to $\pi/24$. The OP needs to be taught to recognize that a change in order of integration can reduce some of these double integrals to simple single integrals. There is a level of thought - at this time, human thought - that the problem deserves, and that someone posting an answer at M.SE needs to describe. This is why CAS-only solutions are unacceptable in many cases, even if the OP only asked for the result of evaluating the integral. But we have generalized hypergeometric and ugly-looking gammas. The sad part is that the answer is quite correct, numerically. Seriously, if you were struggling in Calc III and were presented with this answer, wouldn't you be tempted to give up? To the inexperienced reader trying to learn something, this is enough to discourage. Q: What are the last three digits of $3^$$ These type of questions are better up as a comment, since they donot help the asker in any ways (actually) but only show what's unnecessary concerning an answer.
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