Deducing a $\cos (kx)$ summation from the $e^{ikx}$ summation
65698
Proving $\sum\limits_{k=0}^{n}\cos(kx)=\frac{1}{2}+\frac{\sin(\frac{2n+1}{2}x)}{2\sin(x/2)}$
54294
Can the product $AB$ be computed using only $+, -,$ and reciprocal operators?
76297
What is the inverse of the $\mbox{vec}$ operator?
31076
Roots of unity filter, identity involving $\sum_{k \ge 0} \binom{n}{3k}$
68481
Finite Summation of Fractional Factorial Series
82794
How can we use geometric series in calculating Green's function sum over loop effects
105325
Expansion of $(1+px+qx^2)^8\equiv 1+8x+52x^2+kx^3$...
60470
Sum of truncated Gammas and degenerate
140984
Sum of Cosine/Exponential
155479
Summation of inner products
119552
Summing Finitely Many Terms of Harmonic Series: $\sum_{k=a}^{b} \frac{1}{k}$
14884
Compute a sum with partial fraction decomposition and generating functions
116491
Closed form for $\sum_{k=0}^{m} {\binom {m}{k}} a^{k} (b+ck)^N$
87934
Deducing $\sin x + \cos x \ge 1$ from $(\sin x + \cos x)^2 = 1 + 2 \sin x \cos x$
8705
Evaluation of $\sum_{x=0}^\infty e^{-x^2}$
42326
Complex Analysis Solution to the Basel Problem ($\sum_{k=1}^\infty \frac{1}{k^2}$)
35525
Methods to compute $\sum_{k=1}^nk^p$ without Faulhaber's formula