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1d
reviewed Leave Open Can you help me to solve the recurrence relation $T(n) = T(\sqrt n) + 1 $?
1d
reviewed Leave Open How to find the limit $ \lim_{(x,y)\to (0,0) }\frac{\sin(x^2+9y^2+|x|+|3y|)}{|x|+|3y|} $?
1d
reviewed Leave Open Complex Logarithm and Principal branches
1d
reviewed Leave Open Find $\sin^3 a + \cos^3 a$, if $\sin a + \cos a$ is known
1d
revised If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$.
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2d
comment If GCD of a list of numbers is 1, is it a necessary condition that GCD of at least one pair of numbers from the list should be 1?
Nice observation. Your expression for $\gcd(a,b,c)$ is correct.
2d
revised If GCD of a list of numbers is 1, is it a necessary condition that GCD of at least one pair of numbers from the list should be 1?
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2d
answered If GCD of a list of numbers is 1, is it a necessary condition that GCD of at least one pair of numbers from the list should be 1?
2d
comment Evaluating $\int_0^\infty \frac{1}{(k-1)!} (\frac{x}{y})^{k+1} (1-y)^{-x/y} \, dx$
The reduction i not quite right, we have $dx=y\,du$ and the limits are $u=0$ and $u=1/y$. Looks a lot like a (lower) incomplete gamma function.
2d
comment What is the best trigonometry book available free?
Another oldie is Hall, which I think later became Hall and Knight.
2d
reviewed Leave Open Prove that a $1$-periodic function $\phi$ is constant if $\phi(\frac{x}{2}) \phi(\frac{x+1}{2})$ is a constant multiple of $\phi$
2d
revised If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$.
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2d
comment Conditional Probability of one RV having maximum among three
If $Y\gt Z$ then $Y$ is likely to be "big," so the probability that $X\gt Y$ is for sure less than $1/2$. Nice argument by the way, good use of symmetry.
2d
revised If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$.
added 20 characters in body
2d
revised If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$.
added 24 characters in body
2d
answered If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$.
2d
comment Simplifying this summation
The distribution of $X$ is Poisson parameter $\lambda p$.
2d
comment What is the best trigonometry book available free?
There is no undergraduate level trigonometry really, except a tiny bit incidental to the De Moivre theorem and the definitions of sine, cosine in terms of complex exponentials. The old fashioned trigonometry had more special tricks, important for efficient computation in the days when a calculator was a person who calculated.
2d
comment What is the best trigonometry book available free?
There will be lots, at various levels. Many of the classic trigonometry books are public domain.
2d
comment Example on Complex Number using De moivrs theorem
Typo, it isn't. Somme $i$'s are missing.