Questions tagged [algebraic-equations]
Use this tag for questions related to solving equations involving polynomials.
46
questions
1
vote
1answer
32 views
Need help simplifying a set of equations (and understanding how to solve it)
i have three algebraic expressions, each using the others. in these equations a, b, c and <...
3
votes
4answers
253 views
Roots of a certain sixth order polynomial
I am looking for the roots (or basically any information regarding them) of the sixth order polynomial
$$p(x):=ax^6+(a+1)x^4+2bx^3-b^2$$
for positive, real constants $a,b$.
Since $p(0)=-b^2<0$ and $...
0
votes
0answers
33 views
Reduction of a system of multivariate nonlinear polynomials
I am trying to find a way to simplify a set of multivariate polynomial equations. As an example, given the free variables $\mu_1,\mu_\star,x,\psi_1,\psi_2$, I am specifically interested in the ...
1
vote
3answers
80 views
How to solve Quadratic Equations with an Unknown C and other variables.
For instance $3x^2 - 11x + r$, I understand the value of $r$ is $6$ through trial and error but trial and error is extremely inefficient and time consuming thus not useful in exam situations, How ...
10
votes
2answers
370 views
What's wrong with manipulating this algebraic equation? and why does a manipulated system of equations have a different solution than the original?
I'll give an example for my first question:
$x^2 + x + 1 = 0$
Clearly $x = 0$ and $x = 1$ aren't solutions, so first we can safely divide by $x$:
$x + 1 + 1/x = 0$
By subtracting $1/x$ from both sides ...
4
votes
2answers
124 views
Solve $2x^2+y^2-z=2\sqrt{4x+8y-z}-19$
I am trying to solve the following equation.
$$
2x^2+y^2-z=2\sqrt{4x+8y-z}-19
$$
To get rid of the square root, I tried squaring both sides which lead to
$$
(2x^2+y^2-z+19)^2=16x+32y-4z
$$
which was ...
0
votes
1answer
40 views
Simplify $a.b+c.d$
Suppose that, $(S, +, \cdot)$ is a semiring, where the operations are defined as $x\cdot y=min(x, y)$ and $x + y=max(x, y)$.
Can we further simply the expression $a\cdot b+c\cdot d$?, where $a, b, c, ...
0
votes
1answer
20 views
Resolve 1 equation with 3 unknowns with specific condition for each unknown
I want to find the possible solution of the following problem:
$T_k= 21600$ seconds
$1281.49 < T < 21600 $(T in seconds)
$x$ and $y$ don't have unit
$x$ and $y$ have to be whole number
$x > 0$...
2
votes
1answer
51 views
If $\sum_{i=k}^n {n \choose i} p^{i}(1-p)^{n-i} \approx 0.05$, how can we find $k$?
Let $n$ be any natural number, let $k\in\{0, \dots, n\}$, and let $p \in [0, 1]$.
If $\sum_{i=k}^n {n \choose i} p^{i}(1-p)^{n-i} \approx 0.05$, how can we find $k$ (in terms of $n$ and $p$)?
0
votes
0answers
28 views
Expanding algebraic equations of polynomials.
So suppose we have $G(z+h,w+t)$ where $G$ is an algebraic equation such that $G(z,w)=g_0(z)+g_1(z)w+\cdots+g_m(z)w^m$, each $g_i(z)$ is a polynomial of $z \in \mathbb{C}$, and $w$ is any function.
My ...
-2
votes
1answer
41 views
Solve $3^x+x^3=17.$ [duplicate]
It's a question I find a bit difficult to solve, and the question is:
$$3^x+x^3=17.$$
1
vote
0answers
31 views
How can a field L be a subgroup of the Galois group of the extension L:K?
I am studying the notion of a Galois group, and a remark in my notes is the following:
"$L:K$ an extension. Let $H$ be a subgroup of $Aut(L)$. Let $L^{H}$ be the fixed field of $H$.
If $L \leq G(L:...
0
votes
1answer
106 views
Show that, if a, b, c are real numbers and ac = 2(b + d), then at least one of $x^2 + ax + b = 0$ and $x^2 + cx + d = 0$ has real roots.
Show that, if $a, b, c$ are real numbers and $ac = 2(b + d)$, then, at least one of the equations $x^2 + ax + b = 0$ and $x^2 + cx + d = 0$ has real roots.
I've have tried many times and used ...
0
votes
1answer
71 views
How to find the roots to the polynomial $z^3+z^2+iz^2-z+1+3i$
I'm having a bit of a problem on how to compute forward the values for z from this equation:
$$
z^3+z^2+iz^2-z+1+3i=0
$$
In the question there's given that one solution or root is z=i, by solving ...
0
votes
1answer
38 views
vertical displacement
I have the below HW question:
What I've done is replace t with 2, thus obtaining that the ball is at a height of 1.25m after 2 seconds and hence, it will travel over the net. Am I correct?
0
votes
0answers
38 views
On multiple roots in algebraic closure of a given field
I’m having trouble digesting a fact that popped up in a proof from Lang’s Algebra, page 247, proposition 6.1.
Given an element $\alpha$ algebraic over $k$, and its minimum polynomial $f(X)$ over k, ...
0
votes
1answer
17 views
Problem Following Algebra Steps
I am trying to follow along an answer to a particular question and don't understand one of the steps taken. I don't understand how they got from step 3 to step 4? The steps can be seen below.
I ...
1
vote
2answers
30 views
Problem Following Along Algebra Steps
I have been given a question with the solution. However I am having trouble following the maths steps that have been taken in the solution. I'm unsure how they have gotten from step 1 to step 2, ...
3
votes
4answers
102 views
Is there a better way to solve this equation?
I came across this equation:
$x + \dfrac{3x}{\sqrt{x^2 - 9}} = \dfrac{35}{4}$
Wolfram Alpha found 2 roots: $x=5$ and $x=\dfrac{15}{4}$, which "coincidentally" add up to $\dfrac{35}{4}$. So I'm ...
0
votes
2answers
104 views
Why the definition of Galois group in rotman’s Advanced modern algebra not considering repeated roots
The definition is provided in the upper figure. What if f(x) had repeated roots? Are the roots considered deduplicated such that there’ are less than n roots f(x) have?
As @reuns pointed out, I have ...
0
votes
2answers
51 views
Algebraic solution for a system of algebraic equations?
I was asked about solving algebraically the following system of algebraic equations.
$$f(a,b):=a(1-b)+ab\frac a{a+b}.$$
$$u = f(a,b),\quad v = f(b,a).$$
Solve algebraically $(a,b)$ in terms of $(u,v)$
...
-1
votes
1answer
51 views
The real numbers $a,b,c,d$ satisfy $a^2+b^2+c^2+1=d+\sqrt{a+b+c-d}$. Find the value of $d$. [duplicate]
The real numbers $a,b,c,d$ satisfy $a^2+b^2+c^2+1=d+\sqrt{a+b+c-d}$. Find the value of $d$.
I've been given this question for a class I'm taking and I'm not really sure where to start. I let $\sqrt{a+...
0
votes
1answer
37 views
Solve the equation for x.
solve the following equation for x
$(x^2-8x-3)÷(8x-3)=(x^2+4x+4)÷(4x+4)$
The problem here I am encountering with is figuring out which method to be used here for solving. I am not getting how to ...
0
votes
3answers
54 views
Solve $(1+x)^2=A\sqrt{1+Cx}$ for $x$.
$x>0$, $A>0$ and $C>1$.
I am trying to come up with a closed form expression for $x$, even if it is an approximation.
Any help appreciated.
2
votes
1answer
63 views
how to handle a “Stiff” algebraic equation numerically?
I have a question of great practical importance for me, but I would like to ask it on a bit more of a theoretical mode, because I feel I lack the basic knowledge on it. I would also like to mention ...
3
votes
1answer
140 views
Solving $8x-3+\sqrt{x+2}-\sqrt{x-1}=7 \sqrt{x^2+x-2}$
Solve the equation
$$8x-3+\sqrt{x+2}-\sqrt{x-1}=7 \sqrt{x^2+x-2}$$
I have this idea: set $$\sqrt{x+2}=a , x+2=a^2 , \sqrt{x-1}=b.$$
So $$x-1=b^2 , 2a^2+6b^2 =8b-4$$ and $$x^2+x-2 =a^2b^2$$ and ...
1
vote
0answers
47 views
If $x$ is algebraic over a quotient field $K$ of $A$, then there exists an integral element $cx$ for some $A \ni c \neq 0$.
Let $A$ be a commutative ring, $K$ its quotient field and $x$ algebraic over $K$. This means that there exists a polynomial $f(X)$ with coefficients in $K$ such that $f(x) = 0$. In other words, if ...
asked Jan 9 '19 at 23:47
OlympicComputerChairSitter
18.2k5 gold badges38 silver badges81 bronze badges
0
votes
1answer
71 views
upper and lower limits for finding just one (real) solution of an algebraic equation (degree 5 and lower)
While programming an equation solver (using trial and error), I came across the fact that there are multiple real and complex bounds in which all of the solutions should be. For my case, only real ...
2
votes
1answer
51 views
Solution to $Mx-x^2=0$ where $x^2$ is the square of the elements of vector $x$
I have been trying to find the solutions for
$$Mx=x\circ x$$
where $\circ$ is the element wise product.
One solution is $x=0$. But there is another solution $x\neq 0$, if $M$ has a real positive ...
0
votes
3answers
80 views
Solving algebraic equations involving factorials - without trial and error.
The question is defined as follows:
$$\frac{(x!)^3}{x}-1=3455$$
I first did the basics which was getting rid of the 1 onto the left and getting rid of the $x$, then I factorised both sides to get an ...
4
votes
1answer
294 views
Applying the quadratic Tschirnhausen transformation
As per my previous question, I attempted to take dxiv's approach, though I can't seem to make much headway. Considering the simpler problem $x^3=x+a$ and the substitution $y=x^2+mx+n$, I got the ...
1
vote
1answer
64 views
Proving non-existence of real roots
Prove that for any real numbers $a_{85}, a_{84}, a_{83},\dots ,a_3$ the equation $a_{85}x^{85}+ a_{84}x^{84}+ a_{83}x^{83}+\dots +a_3x^3+3x^2+2x+1=0$ has no real roots. (This problem is stated in ...
0
votes
4answers
143 views
Solving a symmetric equation involving three variables a,b and c
Solve : $$\frac{x+a^2}{a+b}+\frac{x+b^2}{b+c}+\frac{x+c^2}{c+a}=2(a+b+c)$$
I am trying to find a simple technique to solve this equation as there is a pattern in the equation, but I could not do. Any ...
0
votes
1answer
67 views
approximating irrational roots of algebraic equations with the Pierce expansion
Let
$ p (x) = 1 - x \lfloor \frac{1}{x} \rfloor $
then the Pierce expansion of a real number $x \in {R}$ is expressed by
\begin{equation}
x_1 = \sum_{n = 1}^{\infty} (- 1)^{n + 1} \prod_{m = 1}^n ...
0
votes
2answers
132 views
Solving $x^2 y''(x) + 6x y'(x) - 9y(x) =0$ with similar techniques that are used to solve algebraic equations
Consider the ODE
$$x^2 y''(x) + 6x y'(x) - 9y(x) =0 .$$
It is clear that we can solve the ODE by the method of reduction of order. However, if we "see" the function $y$ as some constant just for a ...
1
vote
0answers
21 views
Does this equation imply separation of variables?
I have the following equation:
\begin{equation}
\dfrac{q(t,r)}{s(t,r)}=B(r), \qquad \qquad (1)
\end{equation}
with $q>0$ and $s>0$.
Apart from the trivial case $q(t,r)=\mathrm{const.} \times ...
0
votes
1answer
21 views
Equations of Value Unknown interest rate
i have two question in some assessments, both based on "Equations of Value Unknown interest rate" and two irregular contributions.
I've been over the textbook, and looking along time on line found ...
0
votes
3answers
47 views
Is $-1$ sum of squares in the field $\mathbb{Q(\beta)}$ where $\beta = 2^{1/3}e^{2\pi i /3}$
Prove that $−1$ is not a sum of squares in the field $\mathbb{Q(\beta)}$ where $\beta = 2^{1/3}e^{2\pi i /3}$
My attempt : In fact $\Bbb Q(\beta)$ and $\Bbb Q(2^{1/3})$ are naturally isomorphic. So I ...
-3
votes
2answers
49 views
Two problems on solving equations in rational and integers [closed]
prove that $x^2-2y^2=7$ has infinitely many solutions in integers.
$a$ and $b$ are two non-zero rational numbers.Then if the equation $ax^2+by^2=0$ has a nonzero rational solution $(x_0,y_0)...
4
votes
1answer
1k views
Explanation of the Tschirnhausen transformation
I am studying the resolution of the quintic equations, which involves the so-called Tschirnhausen transform.
The idea is to cancel the fourth and third degree coefficients by a change of variable of ...
3
votes
2answers
235 views
How to find all nonnegative integers $x, y, z$ and $w$ such that $2^x3^y-5^z7^w=1$
Find all nonnegative integers $x, y, z$ and $w$ such that $2^x3^y-5^z7^w=1.$
I think they are $(x,y,z,w)=(1,0,0,0),(1,1,1,0),(3,0,0,1),(2,2,1,1)$, but I couldn't prove its sufficiency (or there may ...
1
vote
1answer
219 views
Find positive integer solutions of cubic equation with three variables
Find positive integer solutions of equation
$$t^3 -at^2 + bt - c=0,$$
where
$$a^3-6ab+7c=0$$
($a, b, c$ are positive integers too).
I've tried to use find solutions in modular arithmetic, but there ...
1
vote
2answers
55 views
Show that $\frac {1}{\sqrt{5}}[(\frac {1}{x+r_+}) - (\frac {1}{x+r_-}) = \frac {1}{\sqrt{5}x}[(\frac {1}{1-r_{+}x}) - (\frac {1}{1-r_{-}x})] $
I need to manipulate this equation:
$$
\frac {1}{\sqrt{5}}\left(\frac {1}{x+r_+} - \frac {1}{x+r_-}\right)
$$
to show that
$$ \frac {1}{\sqrt{5}}\left(\frac {1}{x+r_+} - \frac {1}{x+r_-}\right) = \...
0
votes
1answer
60 views
Is it constant?
Let $G$ be an abelian group, and let $n:G\times G\rightarrow \mathbb{Z}$ be a map satisfying for all $u,v,w\in G$
$$ n(u+v,w)+n(u,v)=n(u,v+w)+ n(v,w)$$ and $n(0,x)=n(y,0)=0$ for all $x,y\in G$
Is $n$...
0
votes
1answer
68 views
Simplify algebraic expression with radicals: $\frac{1- ax}{1+ ax} \cdot \sqrt\frac{1+bx}{1-bx}$
I got stuck trying to simplify this roots forest:
$\frac{1- ax}{1+ ax}*\sqrt\frac{1+bx}{1-bx}$
where x= $\sqrt{\frac{2a}{b}-1}$
So it is:
$\frac{1- a\sqrt{\frac{2a}{b}-1}}{1+ a\sqrt{\frac{2a}{...
0
votes
2answers
84 views
A simple fraction with a complex answer: possibly right under my nose
I've been doing some calculations in fractions, and found this equation pop up to calculate my answer:
$$\frac{1-x}{1+x}=x$$
the initial equation is
$$\frac{2(x-1)}{\frac{4(x+1)}{2}}+x=4x+9(-4x-2)-...
