User Nikola Alfredi

7 votes

3 answers

137 views

Infinite summation : $\displaystyle S= \sum_{r=0}^{\infty} \frac{\cos (2xr)}{4r^2 - 1}$

asked Mar 11, 2022 at 14:33

6 votes

3 answers

333 views

Solution to the $\displaystyle \phi'' + 4\phi' + 3\phi = x \cos {3x}. $

asked Aug 6, 2021 at 17:15

5 votes

1 answer

1k views

7 digit number combinations

asked Feb 27, 2020 at 16:40

5 votes

2 answers

261 views

Computing : $\displaystyle \int \frac {m + n\cos (x-x_0) }{ [a+b\cos (x-x_0)]^{3/2} } \mathrm{d}x $ with integration of $E$ and $F$

asked Mar 23, 2022 at 8:27

3 votes

2 answers

283 views

Number of subsets of $X = $ { $ 1,11,21,31,41,..., 551 $ } such that no two elements sum to $552.$

asked Mar 4, 2020 at 19:19

2 votes

0 answers

68 views

Solving $\displaystyle I = \int_{0}^{1} \left (( \ln u)^{-z} - \sum_{k=0}^{n-1} \frac {(\ln u)^{k-z}}{u \cdot k!} \right ) \mathrm {d}u$ with $z>0$.

asked Aug 26, 2021 at 20:34

2 votes

1 answer

72 views

Where does the Integral went wrong .... $ \displaystyle \int _{0}^{\pi} \frac {\ln ( 1 + \sin \alpha \cos x )}{\cos x} \ \mathrm {d}x $

asked Mar 21, 2021 at 10:39

2 votes

1 answer

176 views

Solving differential equation without IVP or fundamental solution : $\displaystyle \phi ^{"} -x \phi ^{'} + x^2 \phi = 0 $

asked May 23, 2021 at 17:40

2 votes

2 answers

52 views

So Many Gridlines.... Can you reach your destination?

asked Mar 10, 2020 at 14:24

1 vote

1 answer

76 views

Basic definition for beginners and usage of Parity of a permutation

asked Feb 29, 2020 at 11:24

1 vote

2 answers

531 views

If $f(x) =x^{x^{x^{x}}}$, determine the last two digits of $f(17) + f(18) + f(19) + f(20).$

asked Mar 2, 2020 at 16:43

1 vote

2 answers

61 views

Impossible Geometry, I think that the case is not possible, but I might be wrong.

asked Mar 10, 2020 at 11:02

1 vote

0 answers

54 views

Proving the Inequality: $\displaystyle 3( a^2 + b^2 + c^2+d^2) + 4abcd \geq 16$ subject to constraint $ a+b+c+d=4.$

asked Mar 18, 2022 at 15:55

0 votes

1 answer

61 views

Bijective Functions.

asked Mar 4, 2020 at 17:09

0 votes

0 answers

53 views

Recently I found a sequence , for $n(n+1)+1$ form of multiples of 7.

asked Feb 29, 2020 at 18:13

0 votes

1 answer

90 views

Find the number of Ordered pairs $(A,B,C)$ where, $ A \subseteq B $ and $ B \subset C $ and $ C \subseteq X$. Where $X =$ {$1,2,...,n$}

asked Mar 5, 2020 at 9:16

0 votes

3 answers

189 views

Help me out to understand the Text.

asked Mar 6, 2020 at 11:06

0 votes

0 answers

52 views

Inequality Confusion, please guide me. [duplicate]

asked Mar 9, 2020 at 18:21

0 votes

2 answers

77 views

Solving $\int_{-\frac {\pi}{2}}^{\frac {\pi}{2}} \log (1+b \sin x) \sin x\,\mathrm dx$

asked Mar 14, 2020 at 15:57

0 votes

1 answer

54 views

Please Help me with this summation, I can't understand how to start?

asked Mar 26, 2020 at 14:04

0 votes

2 answers

54 views

How to simlpify this Sum?

asked Mar 27, 2020 at 7:55

0 votes

2 answers

144 views

Combinatorial Summation of $ \sum_{n = 0}^{\infty} \binom{2n}{n} {\frac{1}{2^{2n}}} \cos{2n\theta} $.

asked Aug 27, 2020 at 5:17

Stack Exchange Network

22 Questions

Infinite summation : $\displaystyle S= \sum_{r=0}^{\infty} \frac{\cos (2xr)}{4r^2 - 1}$

Solution to the $\displaystyle \phi'' + 4\phi' + 3\phi = x \cos {3x}. $

7 digit number combinations

Computing : $\displaystyle \int \frac {m + n\cos (x-x_0) }{ [a+b\cos (x-x_0)]^{3/2} } \mathrm{d}x $ with integration of $E$ and $F$

Number of subsets of $X = $ { $ 1,11,21,31,41,..., 551 $ } such that no two elements sum to $552.$

Solving $\displaystyle I = \int_{0}^{1} \left (( \ln u)^{-z} - \sum_{k=0}^{n-1} \frac {(\ln u)^{k-z}}{u \cdot k!} \right ) \mathrm {d}u$ with $z>0$.

Where does the Integral went wrong .... $ \displaystyle \int _{0}^{\pi} \frac {\ln ( 1 + \sin \alpha \cos x )}{\cos x} \ \mathrm {d}x $

Solving differential equation without IVP or fundamental solution : $\displaystyle \phi ^{"} -x \phi ^{'} + x^2 \phi = 0 $

So Many Gridlines.... Can you reach your destination?

Basic definition for beginners and usage of Parity of a permutation

If $f(x) =x^{x^{x^{x}}}$, determine the last two digits of $f(17) + f(18) + f(19) + f(20).$

Impossible Geometry, I think that the case is not possible, but I might be wrong.

Proving the Inequality: $\displaystyle 3( a^2 + b^2 + c^2+d^2) + 4abcd \geq 16$ subject to constraint $ a+b+c+d=4.$

Bijective Functions.

Recently I found a sequence , for $n(n+1)+1$ form of multiples of 7.

Find the number of Ordered pairs $(A,B,C)$ where, $ A \subseteq B $ and $ B \subset C $ and $ C \subseteq X$. Where $X =$ {$1,2,...,n$}

Help me out to understand the Text.

Inequality Confusion, please guide me. [duplicate]

Solving $\int_{-\frac {\pi}{2}}^{\frac {\pi}{2}} \log (1+b \sin x) \sin x\,\mathrm dx$

Please Help me with this summation, I can't understand how to start?

How to simlpify this Sum?

Combinatorial Summation of $ \sum_{n = 0}^{\infty} \binom{2n}{n} {\frac{1}{2^{2n}}} \cos{2n\theta} $.