Mathematics
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RDK
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Resting, just uploading my solution of trivial things.

I don't mind any downvotes, just for various solutions.

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All Questions Answers
Score Newest
answer
6
how to calculate the area of ​the painted circle?
Jun 11
answer
5
If $z=-\dfrac12-\dfrac{\sqrt{3}}{{2}}i$, find the value of $z^4+z^8$.
Nov 24, 2021
question
4
Find $f: \mathbb{N_0} \to \mathbb{N_0}$ which satisfies $f^n(x+f(y))=f^{n+1}(x)+f^n(y) \text{ for } n \in \mathbb{N}.$
Jan 5
question
4
Prove that $\sum_{cyc} \frac {a^3+3b^3}{5a+b} \geq \frac 2 3 (a^2+b^2+c^2) \text{ for } a, b, c \in \mathbb{R^+}$
Oct 27, 2021
question
4
Prove that $f(x)^2+f(x+1)^2 = f(2x+1)$ for the function $f$ satisfying $f(x)=f(x-1)+f(x-2), f(1)=f(2)=1.$
Oct 29, 2021
question
3
Finding all $ f: \mathbb{R} \to \mathbb{R}$ such that $ f(x+f(y))=f(x)+2xy^2+y^2f(y) $
Oct 12, 2021
question
3
Finding all the surjective functions $ f: \mathbb{R} \to \mathbb{R}$ which satisfy $f(x+f(x)+xy)=2f(x)+xf(y) \ \forall x, y \in \mathbb{R}$
Oct 18, 2021
question
3
Find the function(s) $f:\mathbb{R}\setminus\{0\}\to\mathbb{R}\setminus\{1\}$, $f(xy)=f(x)f(-y)-f(x)+f(y)$, $f(f(x))=\frac1{f\left(\frac1x\right)}$
Nov 1, 2021
question
3
$abc+a+b+c=ab+bc+ca+5,$ $a, b, c \in \mathbb{R}$. Find the minimum of $a^2+b^2+c^2$.
Nov 9, 2021
question
2
Proving $(ac+bd)^2+(ad-bc)^2=(a^2+b^2)(c^2+d^2)$ with various solutions.
2 days ago

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