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20h
comment Let $f\colon [a,b]\to\mathbb R$ is continuous and $G(x,t)=t(x-1)$ when $t\leq x$ and $x(t-1)$ when $t\geq x$.
Hint: $G(x+h,t)-G(x,t)$ is most of the time either $ht$ or $h(t-1)$
20h
comment Suppose $A$ is a subset of $B$ and $B$ is a subset of $C$ and $A$ is equinumerous with $C$. Prove $B$ is equinumerous with $C$.
@Bernard Not sure, but isn't the prblem claim just as strong as Cantor-Bernstein?
20h
answered Finding the sum of special multiplications
21h
comment What is the “cost” of computation of two special CAS algorithms
If you factor $\sum_{k=0}^n d_kX^k$, you get a factorization of $\sum_{k=0}^n d_k10^k$ for free (though some factors like $X-9$ might lead to trivial factors of the latter)
21h
answered Suppose $A$ is a subset of $B$ and $B$ is a subset of $C$ and $A$ is equinumerous with $C$. Prove $B$ is equinumerous with $C$.
21h
revised Suppose $A$ is a subset of $B$ and $B$ is a subset of $C$ and $A$ is equinumerous with $C$. Prove $B$ is equinumerous with $C$.
Adjust title to match body
21h
revised Suppose $A$ is a subset of $B$ and $B$ is a subset of $C$ and $A$ is equinumerous with $C$. Prove $B$ is equinumerous with $C$.
Adjust title to match body
21h
comment Find the smallest $N$ such that $\sum_{k=1}^N\frac{1}{p_k}>\pi$. (The $p_k$'s are the prime numbers.)
Just to put this in perspective: With $N=3260806$, we have $\log\log(\frac N{\log N}+1)-\log{\frac{\pi^2}6}\approx 2.01$, which is way off. To get anywhere near $\pi$, you'd need $N\approx 10^{18}$ and surely don't want to work backwards from there
21h
comment How can I find the radius and interval of convergece of $\sum_{n=0}^\infty {(x+5)^n} $, and for what value of x does the series converge?
also: root test
21h
revised Power to which 7 is raised to produce a number starting with 2015…
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21h
answered question regarding group permutation computation
21h
comment Prove that $F=\left(-x^2+2\right)\cdot \cos\left(x\right)+2x\sin\left(x\right)$ don't have limit
@AndreiMihai Not even that (alos, $f$ and $F$ are not periodic strictly speaking). It is enough to have long enough intevals at hand where we can nicely estimate from below. Starting with the even more nonperiodic $f(x)=x^2\sin(x^2)$ the above method still leads to success.
21h
revised Power to which 7 is raised to produce a number starting with 2015…
added 1672 characters in body
22h
answered Power to which 7 is raised to produce a number starting with 2015…
22h
comment How calculate the probability that there is a row in which there is no silver coin?
How do governments enter this scene?
22h
revised Proof of linear independence of non-empty subsets
rolled back to a previous revision
22h
answered Proof of linear independence of non-empty subsets
22h
revised Proof of linear independence of non-empty subsets
rolled back to a previous revision
22h
revised Proof of linear independence of non-empty subsets
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22h
revised Prove that $F=\left(-x^2+2\right)\cdot \cos\left(x\right)+2x\sin\left(x\right)$ don't have limit
added 10 characters in body; edited title