Some multivariable calculus problems

Here are some problems of multivariable calculus.

https://www.dropbox.com/sh/vxpjv8wejpy0fb3/XJ3ulE7m85

Do anyone knows is answers? Just the answers will be fine, but with steps is even better if you are convinient.
Many thanks.

sorry Summer but in general that's not how it works here. You have to give the problems a try. Post what you've tried here and then ask specific questions about where you got stuck.

We're here to help you do your work. Not to do it for you.
 
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