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4h
comment For every integer vector $\overrightarrow{a}$,there is a integer vector $\overrightarrow{b}$ such that $\overrightarrow{a}\bot\overrightarrow{b}$
Fair enough. How would you define cross product in $\Bbb R^n$?
4h
comment For every integer vector $\overrightarrow{a}$,there is a integer vector $\overrightarrow{b}$ such that $\overrightarrow{a}\bot\overrightarrow{b}$
What's with all the periods?
10h
comment Revised proof for the set of positive irrational numbers closed under multiplication*
What does $\overline{\Bbb Q}^+$ mean? I assume it's the complement of $\Bbb Q$ in $\Bbb R^+$?
14h
comment Show that if $f$ is continuous at $a$ and $f(a)≠0$ then $f$ is nonzero in an open ball around $a$.
Note: $n$ already means something very specific. Do not use it in another way.
14h
comment Show that if $f$ is continuous at $a$ and $f(a)≠0$ then $f$ is nonzero in an open ball around $a$.
Because $f^{-1}(V)$ is open, and you can make $2r$ as small as you like.
16h
revised Show that if $f$ is continuous at $a$ and $f(a)≠0$ then $f$ is nonzero in an open ball around $a$.
made title useful
16h
answered Open-Set Correspondence $\implies$ Continuity
16h
comment If the surface area of a box is 32 and its volume is doubled what is the new surface area?
It depends on how the volume is doubled. Do we simply double its length, for example? Do we quadruple its length and cut its width in half? Do we multiply each dimension by $\sqrt[3]2$? Do we miltiply two of the three dimensions by $\sqrt2$?
16h
comment If the surface area of a box is 32 and its volume is doubled what is the new surface area?
The keyword, here, is "if".
16h
comment If the surface area of a box is 32 and its volume is doubled what is the new surface area?
The keyword, here, is "if".
17h
comment Finding the equation of a curve where the gradient is $ax + b$ at all points.
Well, you know that $ax+b=0$ when $x=3,$ and so....
21h
comment Finding the equation of a curve where the gradient is $ax + b$ at all points.
So, what does that tell you about $3a+b$?
22h
answered Finding the equation of a curve where the gradient is $ax + b$ at all points.
1d
comment simplifying set theory expression
You are correct that $Z$ may contain some members of team $A$, but will include all who are members of team $A$ and at least one other team.
1d
comment simplifying set theory expression
If all are in at least one team, then $A^c$ is a subset of $Z$, so $A^c\cup Z=Z.$
1d
revised simplifying set theory expression
added 298 characters in body
1d
revised simplifying set theory expression
added 298 characters in body
1d
answered simplifying set theory expression
1d
revised Problem with line equation with double equal signs
edited body
1d
revised Equation of plane through intersection of planes and parallel to line
deleted 4 characters in body