64 is a constant, so the answer remains the same whether you have the 64 or you don't have it. Wolfram's answer is different than yours in that they have the constant of integration where your constant is c.
This is what I did:
Therefore, I have:
Subbing back in, I get
which when expanded out gives me
Then, quartering everything:
The problems is that Wolfram Online Integrator does not include the final term "64" in the answer.
Where have I gone wrong??
Thanks in advance