User Fareed Abi Farraj

16 votes

Why can I solve an impossible equation using linear algebra?

answered Nov 25, 2019 at 13:38

9 votes

Are there any other methods to apply to solving simultaneous equations?

answered Apr 9, 2019 at 7:43

7 votes

Given $\mathbb E(5X+2)=12$ and $\mathbb E(X|Y)=Y^3$ compute $\mathbb E(Y^3)$

answered Mar 27, 2019 at 20:31

6 votes

Intuition behind determinant of a matrix with $2$ equal rows

answered Apr 23, 2019 at 11:47

5 votes

Accepted

There are 4 identical oak trees, 2 identical maple trees and 3 identical pine trees. How many arrangements start with maples?

answered Nov 28, 2019 at 9:42

4 votes

Accepted

Is it correct to assume that if $n \in \mathbf{Z}_+$ then $ \Big|\frac{\sin(n)}{2^n}\Big| \leq \Big|\frac{1}{2^n}\Big|$?

answered Nov 28, 2019 at 9:19

4 votes

Accepted

How to integrate $\ln(2+\sin x)$

answered Nov 19, 2019 at 11:01

4 votes

Accepted

Suppose $BA$ is nilpotent, is it always true that $AB$ is nilpotent?

answered Mar 31, 2019 at 15:47

4 votes

Accepted

Mathematical average formula

answered Aug 24, 2019 at 20:08

4 votes

Area of quadrilateral using determinant/cross product

answered Aug 26, 2019 at 21:00

4 votes

How many 6-digit numbers are divisible by 7?

answered Oct 4, 2019 at 20:45

3 votes

In modern algebra, what does $(m,n)=1$ mean?

answered Jul 29, 2019 at 20:29

3 votes

How to solve this equation without using "observation"

answered Apr 12, 2019 at 7:56

3 votes

Complex numbers $z=-3-4i$ polar form

answered Apr 25, 2019 at 16:35

3 votes

Accepted

Find measure of angle $x$

answered Nov 16, 2018 at 11:25

3 votes

Accepted

Is there a way to find $\cos(a+b)$ and $\cos(a-b)$ in terms of $\tan a$ and $\tan b$?

answered Nov 27, 2018 at 5:06

3 votes

Accepted

There are 3 red balls and 2 white balls in a box.

answered Dec 10, 2019 at 8:06

3 votes

Accepted

Showing expression of $dA$ in cartesian coordinates = $dA$ in cylindrical polar

answered Dec 29, 2019 at 14:37

3 votes

How to find an inverse of this type of functions?

answered Mar 22, 2020 at 16:59

2 votes

Why does a polynomial with real, simple roots change its sign between its roots?

answered Jan 6, 2020 at 20:06

2 votes

Accepted

In how many ways can 4 cards be drawn randomly from a pack of 52 cards such that there are at least 2 kings and at least 1 queen among them?

answered Sep 20, 2020 at 3:39

2 votes

Textbook question about inner product and work.

answered Sep 20, 2020 at 19:24

2 votes

Prove that a tree with a vertex $v$ of degree $k > 1$ has at least $k$ leaves

answered Dec 8, 2019 at 14:54

2 votes

Number of ways to insert parentheses between elements

answered Dec 29, 2019 at 13:53

2 votes

Accepted

Let A, B, C be sets.

answered Nov 21, 2019 at 22:54

2 votes

Accepted

Understanding the limit $n \to \infty$ of the sequence $a_n := \frac{n!}{3^n}, n \in \mathbb{N}$

answered Nov 28, 2019 at 9:26

2 votes

Accepted

How do I solve $3xy=4xz=5yz$ ${x+y \over x-z}=?$

answered Nov 28, 2019 at 19:32

2 votes

If $C(16,r) = C(16,r+2)$, then find $r$. Explain how you know.

answered Dec 3, 2018 at 4:41

2 votes

How many 4 digit numbers can be formed by digits 3, 1, 3, 1?

answered Dec 15, 2018 at 8:55

2 votes

Accepted

Using derivatives to compute velocity if only displacement is given

answered Sep 4, 2018 at 8:18

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189 Answers

Why can I solve an impossible equation using linear algebra?

Are there any other methods to apply to solving simultaneous equations?

Given $\mathbb E(5X+2)=12$ and $\mathbb E(X|Y)=Y^3$ compute $\mathbb E(Y^3)$

Intuition behind determinant of a matrix with $2$ equal rows

There are 4 identical oak trees, 2 identical maple trees and 3 identical pine trees. How many arrangements start with maples?

Is it correct to assume that if $n \in \mathbf{Z}_+$ then $ \Big|\frac{\sin(n)}{2^n}\Big| \leq \Big|\frac{1}{2^n}\Big|$?

How to integrate $\ln(2+\sin x)$

Suppose $BA$ is nilpotent, is it always true that $AB$ is nilpotent?

Mathematical average formula

Area of quadrilateral using determinant/cross product

How many 6-digit numbers are divisible by 7?

In modern algebra, what does $(m,n)=1$ mean?

How to solve this equation without using "observation"

Complex numbers $z=-3-4i$ polar form

Find measure of angle $x$

Is there a way to find $\cos(a+b)$ and $\cos(a-b)$ in terms of $\tan a$ and $\tan b$?

There are 3 red balls and 2 white balls in a box.

Showing expression of $dA$ in cartesian coordinates = $dA$ in cylindrical polar

How to find an inverse of this type of functions?

Why does a polynomial with real, simple roots change its sign between its roots?

In how many ways can 4 cards be drawn randomly from a pack of 52 cards such that there are at least 2 kings and at least 1 queen among them?

Textbook question about inner product and work.

Prove that a tree with a vertex $v$ of degree $k > 1$ has at least $k$ leaves

Number of ways to insert parentheses between elements

Let A, B, C be sets.

Understanding the limit $n \to \infty$ of the sequence $a_n := \frac{n!}{3^n}, n \in \mathbb{N}$

How do I solve $3xy=4xz=5yz$ ${x+y \over x-z}=?$

If $C(16,r) = C(16,r+2)$, then find $r$. Explain how you know.

How many 4 digit numbers can be formed by digits 3, 1, 3, 1?

Using derivatives to compute velocity if only displacement is given