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Apr
18
revised Proving a complicated identity
added 152 characters in body
Apr
17
revised How to solve this complex logarithm equation?
added 337 characters in body
Apr
15
revised How to sum $\sum_{k=1}^n (k+1)(k)(k-1)$
added 317 characters in body
Apr
12
revised Limit w/o L'hopital
added 65 characters in body
Apr
12
revised Let $a$ be a quadratic residue modulo $p$. Prove that the number $b\equiv a^\frac{p+1}{4} \mod p$ has the property that $b^2\equiv a \mod p$.
added 107 characters in body
Apr
11
revised Evaluating indefinite integral using substitution
added 66 characters in body
Apr
11
revised Solve $\frac{(x-1)^{204}(x+3)^5(x-4)^{2015}}{(x+5)^{102}}\ge 0$
added 88 characters in body
Apr
11
revised Find $f$ if $f ''' (x) = \sin(x), f(0) = 4, f '(0) = -5, f ''(0) = -9$
added 1 character in body
Apr
10
revised Where does this equation come from: $ (1+mx)^n = 1 + \sum_{n=1}^{\infty} {\binom{2n}{n} \over 4^n } x^n $
added 4 characters in body
Apr
9
revised Summation of $\frac {n^a}{n!}$
added 124 characters in body
Apr
9
revised What is $\tan \alpha$ if $\sin \alpha + \cos \alpha = \frac{\sqrt{3}-1}{2}$ and $\alpha \in (90^\circ,135^\circ)$
added 306 characters in body
Apr
8
revised Find the last three digits of $17^{256}$
added 249 characters in body
Apr
8
revised Sum of coefficients in an multinomial expression.
added 30 characters in body
Apr
7
revised Integrate with which technique
added 4 characters in body
Apr
6
revised How to prove that $ \sum_{k=1}^{n-1} \frac{1}{1-e^{2 \pi i k/n}} = \frac{n-1}{2}$?
added 106 characters in body
Apr
4
revised Find $3^{2015} + 7^{2015}\bmod50$
added 253 characters in body
Apr
4
revised If $n$ is a positive integer such that $2^n+n^2$ is a prime number , then is it true that $6|n-3$ ?
added 255 characters in body
Apr
3
revised $x^3-3x^2+(a^2+2)x-a^2$ has 3 roots $x_1,x_2,x_3$ such that $\sin \tfrac{2\pi x_1}{3}+\sin \tfrac{2\pi x_3}{3}=2\sin \tfrac{2\pi x_2}{3}$. Find $a$.
added 134 characters in body
Apr
2
revised Find all values of $x$, linear and quadratic functions
added 40 characters in body
Apr
1
revised Proving $\sum\limits_{k=1}^{2n} {(-1)^k \cdot k^2}=(2n+1)\cdot n$ for all $n\geq 1$ by induction
added 168 characters in body