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Jun
6
answered If $f(x,y,z)=(r \times A)\cdot (r\times B)$, where $r=(x,y,z)$, show that $\nabla f(x,y,z)=B\times (r\times A)+A\times (r\times B)$.
Jun
6
answered What is the level set of 1D function?
Jun
6
revised what is the parametric form for “mystery curve”?
added 72 characters in body
Jun
5
revised Quotient rule in multivariables wrong?
added 19 characters in body
Jun
5
revised what is the parametric form for “mystery curve”?
added 123 characters in body
Jun
5
answered what is the parametric form for “mystery curve”?
Jun
5
answered Calculus made easy Exercise 9 Question 4 (Doubt)
Jun
4
comment Find the number of positive integers solutions of the equation $3x+2y=37$
The equation $x+y=8$ has $7$ solutions. According to your argument the equation $3x+2y=8$ would have ${7\over6}$ solutions.
Jun
4
comment What is the technical difference between a formal and informal power series?
For an introduction to formal power series see the first chapter of Peter Henrici's Applied and computational complex analysis.
Jun
3
answered Explain the geometrical interpretation a pair of harmonic function conjugated each other.
Jun
3
comment Work Problem that deals with Number of Men, Days, Leaving
My grandchildren routinely solve such problems in a high school ("Gymnasium") acceptance test. Sometimes it's about how many days longer a supply of hay lasts when three of the 25 cows suddenly died.
Jun
3
comment Is the zero vector in the definition of linear dependence arbritary?
If ${\bf 0}$ and ${\bf 0}'$ are zero vectors, i.e. both "neutral" with respect to addition, then ${\bf 0'}={\bf 0'}+{\bf 0}={\bf 0}$.
Jun
3
answered Quotient rule in multivariables wrong?
Jun
3
revised What's the meaning of having ^ over a vector name?
added 143 characters in body
Jun
2
answered In order to show that a function is C^1 is it enough to show that the 1. partial derivatives exists?
Jun
2
comment How can we count in base eleven?
@CSCFCEM: Check your counting!
Jun
2
comment Proof of Number of: *permutations of ‘n’ things, taken ‘r’ at a time, when ‘m’ specified things always come together*
The text underlined in beige is fishy. A variable $r$is introduced in the formulation of the problem, but it does not appear in the result. What do you mean by "taken $r$ at a time"?
Jun
2
comment how to check this function is not complex differentiable in 0
@Andrew: A function which is not even bounded near $z=0$ cannot be continuous at $0$, let alone be differentiable in any sense.
Jun
2
revised how to check this function is not complex differentiable in 0
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Jun
2
answered What's the meaning of having ^ over a vector name?