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Need help, URGENT maths question: (3 Viewers)

1008

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Well it's because the notations are both referring to the partial derivative of ƒ wrt its first designated variable. As seanieg89 said:

.
Thanks so much InteGrand for clearing that up. Yeah I knew that x and u are dummy variables, but I couldn't translate my understanding in my previous answer, I guess substituting u and v indeed make the notation a little less chaotic lol... How would you do this one?

 

InteGrand

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Thanks so much InteGrand for clearing that up. Yeah I knew that x and u are dummy variables, but I couldn't translate my understanding in my previous answer, I guess substituting u and v indeed make the notation a little less chaotic lol... How would you do this one?

What have you gotten up to so far? The first part of doing part (a) (just setting up the Riemann sum) should be rather routine. What did you get for the Riemann sum?
 

1008

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Alright, I've got another question:



For the second question, in the answers they implicitly differentiate the equation wrt x and y and then the normal is the vector: . I just wanna know why they always use -1 for the third element of this vector, and is there an alternate way of doing this question? And can we pick any number instead of -1?

EDIT: Sorry for being cold and not replying to your previous post IG, I was heading to uni when you replied, and I had work after. And then I've been busy with exams prep D: I'm still working on those q's, but I'm finishing off other subjects first
 
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InteGrand

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Alright, I've got another question:



For the second question, in the answers they implicitly differentiate the equation wrt x and y and then the normal is the vector: . I just wanna know why they always use -1 for the third element of this vector, and is there an alternate way of doing this question? And can we pick any number instead of -1?

EDIT: Sorry for being cold and not replying to your previous post IG, I was heading to uni when you replied, and I had work after. And then I've been busy with exams prep D: I'm still working on those q's, but I'm finishing off other subjects first
No worries. :)





 
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InteGrand

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Alright, I've got another question:



For the second question, in the answers they implicitly differentiate the equation wrt x and y and then the normal is the vector: . I just wanna know why they always use -1 for the third element of this vector, and is there an alternate way of doing this question? And can we pick any number instead of -1?

EDIT: Sorry for being cold and not replying to your previous post IG, I was heading to uni when you replied, and I had work after. And then I've been busy with exams prep D: I'm still working on those q's, but I'm finishing off other subjects first


 

leehuan

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No worries. :)





Holy crap. This took me one whole semester to finally understand what is going on.
_______

Also @1008

I'm pretty sure Ian has the proof of why the normal vector is IG's correction in his lecture slides.
 

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