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Mar
23
comment k nearest points
a nearest 1 neighbor does not necessarily exist, e.g there is no nearest k neighbor for k=1 in a regular polygon
Mar
23
comment Proving the cardinality of finite sets
another way may be to construct a bijection between these two sets. If such one exists their cardinality is the same
Mar
23
comment How to prove that $\max(\min(g,M),-M)$ is close to $f$, given $g$ is close to $f$
besides that, why should g be a function from R^n intead of K. In all expressions it is restricted to K.
Mar
23
comment How to prove that $\max(\min(g,M),-M)$ is close to $f$, given $g$ is close to $f$
I already mentioned that it is sufficient to show it for numbers f and g. To show it for numbers you have to check different cases
Mar
23
comment How to prove that $\max(\min(g,M),-M)$ is close to $f$, given $g$ is close to $f$
can you tell us where you found this problem?
Mar
23
comment How to prove that $\max(\min(g,M),-M)$ is close to $f$, given $g$ is close to $f$
I tthink it does not make sense to pose this question for functions because all definitions are pointwise. so it is sufficient to show this for numbers g and f
Mar
23
comment How to prove that $\max(\min(g,M),-M)$ is close to $f$, given $g$ is close to $f$
it does not makes sense to define g a funczion from R^n instead of K because f-g and the max-min expression ins only defined over K.
Mar
10
comment Solve in positive integers the equation $a^3+b^3=9ab$
From your inequalities you get $a^2b^2\lt 81ab$ and so $ab\lt 81$. if $a\le b$ then $a^2\lt 81$
Mar
3
comment Factor $16x^4-x^2y^2+y^4$
He wants to factor the right side of the equation.
Mar
3
comment Trivial solution when solving in integers
another contradiction: $3|3t^2 \implies 3|(13s^2-24s) \implies 3^2|13s^2-24s \implies 3|t \implies 3|\gcd(s,t)$
Feb
29
comment How do you sketch the LHS and RHS on one pair of axes and then solve
@Galc127: so $|a|\ge |b|$ if $a=-1$ and $b=-5$
Feb
29
comment How do you sketch the LHS and RHS on one pair of axes and then solve
How do you graph |x-1|?
Feb
23
comment What is $R\circ S$? For$ s = \{(1,2),(1,3),(2,3),(2,4),(3,1)\}$ and …
same quesion
Feb
23
comment Prove a formula is not a logical consequence of KB
@Wojowu: How do you write a comment with less than 15 characters?
Feb
20
comment Prove that $a^5 ≡ a$ (mod 15) for every integer $a$
It is sufficient to proof this for a=0,...,14
Feb
18
comment Eliminating a variable using three equations
Did you already try to disprove it by choosing numbers that satisfy the first three equations and insert them in the fourth equation?
Feb
17
comment Finitely differentiable function
$|x|$ isn't differentiable at 0. From this you can construct a function whose k-th derivate is $|x|$ and therefore its (k+1) derivate does not exist at 0.
Feb
17
comment What is wrong with the given proof?
duplicate: math.stackexchange.com/q/1493827/11206 math.stackexchange.com/q/117998/11206
Feb
16
comment If $x^2+y^2-xy-x-y+1=0$ ($x,y$ real) then calculate $x+y$
If it is required that $(x,y) \in \mathbb{R}^2$, then you should add this requirement to your post.
Feb
11
comment The accuracy from left to right and that from right to left of the floating point arithmetic sums
@probablyme: I think it is not necessary to add a link "Source" to the üicture of the text. This link can be found in the older versions of the posr.