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1d
comment How prove this $\sum_{cyc}\frac{x+y-2z}{(x+y)^2+z^2}=0$
Write $$x+y-2z=y-z-(z-x), y+z-2x=z-x-(x-y)$$ then factor out $z-x$ etc.
1d
comment Calculate $\frac{1}{5^1}+\frac{3}{5^3}+\frac{5}{5^5}+\frac{7}{5^7}+\frac{9}{5^9}+\cdots$
Related: math.stackexchange.com/questions/533039/… and math.stackexchange.com/questions/633784/…
2d
answered Prove that $17$ divides $9a + 5b$
2d
comment Which one is correct for $\sqrt{-16} \times \sqrt{-1}$? $4$ or $-4$?
@cirpis, en.wikipedia.org/wiki/…
2d
comment Which one is correct for $\sqrt{-16} \times \sqrt{-1}$? $4$ or $-4$?
@cirpis, Also, when we write $a\ge0,$ we implicitly assume $a$ to be real, right as we can not say $P+iQ\ge$ or $\le0$ for real $P,Q$
2d
comment Which one is correct for $\sqrt{-16} \times \sqrt{-1}$? $4$ or $-4$?
@cirpis, Even in complex domain, for $a,b>0 \sqrt{-a}\sqrt{- b}=i\sqrt a\cdot i\sqrt b=-ab$ right? and not $\sqrt{-a}\sqrt{- b}=\sqrt{(-a)(-b)}=\sqrt{ab}$
2d
answered Which one is correct for $\sqrt{-16} \times \sqrt{-1}$? $4$ or $-4$?
2d
comment Prove that there exists $s$ such that $s(ab-1)^n +1$ is composite
@primitiveroot, Can you please certify Ehsan's statement?
2d
comment Prove that there exists $s$ such that $s(ab-1)^n +1$ is composite
$$s\equiv(-1)^{n+1}\pmod{ab}\implies s(ab-1)^n\equiv-1\pmod{ab}$$
2d
comment Proving the following proportion
@user3650050, See math.stackexchange.com/questions/875778/…
2d
comment Sides and angles of a triangle
@user3650050, How about this?
2d
answered Sides and angles of a triangle
2d
comment How do i calculate the value of $\int_{0}^{1} \frac{\ln{(1+x)}}{1+x^2}$?
math.stackexchange.com/questions/220746/…
Jul
23
answered If $a^2=b^2+c^2$ and $0<n<2$ prove $a^n<b^n+c^n$
Jul
23
comment What is the remainder when the below number is divided by $100$?
@WannaBeCoder, It's called en.wikipedia.org/wiki/Binomial_theorem
Jul
23
comment Find value of $x$ for: $(1/3)(1-x) \geq 2(x-3)$
@BarryCipra, Thanks for your observation
Jul
23
revised Find value of $x$ for: $(1/3)(1-x) \geq 2(x-3)$
edited body
Jul
22
revised What is the remainder when the below number is divided by $100$?
added 279 characters in body
Jul
22
revised What is the remainder when the below number is divided by $100$?
added 279 characters in body
Jul
22
answered What is the remainder when the below number is divided by $100$?