Questions tagged [equation-solving]

Questions on the analytic and numerical equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).

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13 views

Solve::nsmet error message while trying to find symbolic solution for equation

I would like to solve several equations for x and I'm looking for symbolic solutions. The later ones might have some rather difficult or no result at all, but I ...
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3answers
66 views

Revolve a function around the x-axis and getting the 3D-model

I have the following differential equation: $$\pi\cdot\left(\text{y}(x)\right)^2=\sqrt{1+\left(\text{y}'(x)\right)^2}\tag1$$ With the initial condition $\text{y}(0)=1$. Now, I want to plot the ...
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52 views

Integration of a fraction function by RootSum or Rubi

I'm trying to solve an integral of p[Tau,r] function: ...
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28 views

How to iterate an answer to an equation using known values?

I have no idea how or where to start, I don't have to vocabulary or terms so let's ask the community. Problem: I have a known value X that is the answer of the equation. I have a range of known values,...
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1answer
29 views

How to solve for y for a set of implicit (in x and y) linear equations for use in Plot?

From a matrix m={{1, 1}, {-1, 1}}, a vector b={1, 2}, and a list of variables vars={x,y} we ...
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24 views

Mathematica does not stop running when trying to reduce a inequality

I have a problem when running the command as Mathematica never stops running. I wonder if it's because there are too many solutions or just because I wrote something wrong. Thanks for your help. The ...
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1answer
58 views

Solving three non-linear ODEs analytically in one variable

Any idea what is the best way to substitute to analytically solve these equations in y(x) ? ...
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1answer
61 views

How to solve this equation with rank relation of matrix

It has been known that matrix A is equivalent to matrix B, and I want to find the possible value of parameter ...
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20 views

What class order should I use to study calculus? [closed]

I would like to know how I should go about studying calculus, and in what order should I take the classes. I have searched tirelessly for answers and I am still confused. Here is what I have gathered ...
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1answer
217 views

How can I find a functional square root in Mathematica?

A functional square root of a function $g$ is another function $f$ such that $g=f\circ f$. According to that article, there is a systematic approach to finding a functional square root that involves ...
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62 views

How to eliminate the list case by `Eliminate` function

It is known that line L1: $\frac{x-a_{2}}{a_{1}}=\frac{y-b_{2}}{b_{1}}=\frac{z-c_{2}}{c_{1}}$ and line L2: $\frac{x-a_{3}}{a_{2}}=\frac{y-b_{3}}{b_{2}}=\frac{z-c_{3}}{c_{2}}$ intersect at a point. Now ...
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1answer
34 views

How to define a function to decouple equations and transform them into standard form

I want to convert this expression($\frac{x-a 2}{a 1}=\frac{y-b 2}{b 1}=\frac{z-c 2}{c 1}$) of the linear equation into a standard form $\left\{\begin{matrix} \text { b1 } * x-a 1 * y=a 2 * b 1-a 1 * ...
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25 views

Reduce does not solve a system of equations

I am trying to solve a system of 7 equations and 7 unknowns given a set of assuptions. I am only interested in obtaining V3 as a function of the exogenous parameters. I am using the following code: <...
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0answers
42 views

How can I convert a list of rules into a list of equations? [closed]

How can I convert a list of solutions to a list of equations? For example, say I have: sol = {{a->1},{b->2}} and I would like to change it to ...
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1answer
52 views

Solve with > instead of == [duplicate]

I want to solve a complicated equation with the sign > instead of ==. However, mathematica Solve function is not defined for >. Can somebody tell me how to do it? Code example: ...
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30 views

Solve with Trig cycled variables

eqn={p2 == u^2 + v^2 - 2 u v csal, q2 == v^2 + w^2 - 2 v w csbt, r2 == w^2 + u^2 - 2 w u csgm} Solve[eqn, {u,v,w}] Hangs indefinite. How to Solve... using ...
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2answers
82 views

Solve system of equations with integration over regions

I want to solve the following problem in Mathematica: Assume that $\lambda_2=-\frac{1}{2}+ r+\frac{1}{1+r}- r^2\log\frac{1+r}{r}$, $v\in[0,1]$ and $\theta\in[0,1]$. For pre-specified values of $k,r>...
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66 views

Groebner Basis for Functions

We can use Reduce to solve the following Reduce[1 - Sqrt[a^(-1)] + Sqrt[2]*Sqrt[(a + a^2)^(-1)] - Sqrt[2 - 2/(1 + a)] == -1 + Sqrt[2], a, Reals] We can also do ...
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2answers
409 views

Why is Mathematica taking so long to solve this equation?

I was trying to solve a polarization problem where I needed to solve this transcendental equation. NSolve[(Cos[\[Pi]/n])^(2 n) == 0.90, n] I don't know why but ...
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1answer
75 views

Plotting in for loop

I am having some problem while plotting the data being generated in for loop My aim is to plot the result of for loop while it is solving the equation for each value of w,i.e. plot between w and x ...
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2answers
386 views

Finding the intersection(s) of a 3D parametric surface and a line

I have some 3D parametric curve par and some line line. I want to find parameters u,v and t for the intersection points of par and line. I tried to do that with NSolve in many different ways and ...
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2answers
139 views

Solve with inverse trig functions (4-Bar Linkage)

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1answer
61 views

How o use singular value decomposition function to find the natural frequency and mode shapes

I have a matrix R which is having a dependency on ω, I am interested in finding the natural frequency and mode shapes of this matrix using SVD how to do this?. The regular way is to take the ...
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2answers
152 views

How to solve a nonlinear second order ODE

I want to solve this equation y''[x] + a + b y[x] + c y[x]^2 == 0, y[∞] == 0, y'[∞] == 0 where a, ...
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1answer
108 views

How to solve a differential equation involving LaplaceTransform?

currently I'm working on a problem in which I need to solve an equation of the following form: $$\mathcal{L}\left[\frac{\partial f(x,t) }{\partial x} + \frac{\partial f(x,t)}{\partial t}\right] = \...
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33 views

Exiting CrossSlidingDiscontinuity in NDSolve to follow equilibrium curve

I am trying to figure out how to get the solution curve to an NDSolve to slide along once it reaches a boundary and then to exit the ...
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0answers
41 views

Solving a cubic equation in mathematica

I am trying to solve a cubic equation using Mathematica of a rather complicated expression say $f(r,\beta,\theta)$ , and in terms of $r$ the maximum degree term that appears is of degree $3$ so I ...
2
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2answers
115 views

How to solve Nonlinear coupled ODEs using DSolve

I cannot solve such a system of coupled ODEs in MMA 12.1 using DSolve. i.e. output is equal to the input equations ... (see the attached figure) Here, each solution is labeled according to the name of ...
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1answer
48 views

Says that my variable is 45 degrees and not valid [closed]

I tried to run Solve[2x+1==6,x] and it has given me an error saying 45 degrees is not a valid variable. How do I fix this?
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1answer
69 views

How to fix the Y-axis and normalize density?

I want to plot a density curve but when I draw the y-axis not getting to 1 (as normalized) ...
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1answer
57 views

How to do Interpolation to this function after given b this values

\[Chi][b_] := (Z/k)*NIntegrate[Subscript[f, pp1][q]*Subscript[F, pp1][q]*BesselJ[0, q*b]*q, {q, 0, b}]; bList = Table[b, {b, 0, 5.1 , 0.05}] where: Z = 6; k=1....
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1answer
35 views

How to find the roots of a transcendental equation that depends on Bessel functions? [duplicate]

I am very new in wolfram mathematica, so i am having trouble in trying to find the roots for this transcendental equation. I am looking for roots of m. Acctually the first non zero value for m. Here J ...
2
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1answer
112 views

Solve a system of differential equations

How to solve this system of equations?
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1answer
227 views

How to solve the differential equation

I need to solve the differential equation DSolve[{(1-x)y''[x]==1/5 \[Sqrt](1+y'[x]^2),y[0]==0,y'[0]==0},y[x],x] but the result given seems to be incorrect and ...
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0answers
16 views

How to solve an equation by substituting possible solutions? [duplicate]

I wish to solve this equation for kappa, given a certain set of parameters (m and beta): ...
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0answers
51 views

Help me factor this equation

I have the following equation: $$\frac{2\left(a A_3 r + \frac{1}{2} r^2 a'^2 \right)}{a^2 r^2}=\frac{8 G \pi \rho}{3}-\frac{c^2 k}{a^2}$$ ...
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1answer
139 views

Implementation of the general solution of Abel differential equation of the second kind in Mathematica

Introduction An Abel equation of the second kind in its canonical form is writen as $$y(x)y'(x)-y(x)=f(x)\quad (6)$$ for arbitrary $f(x)$. Despite the fact that this equation has general solutions 1 ...
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1answer
82 views

Mathematica does not solve system of equations

I am trying to solve a system of 7 equations and 7 unknowns given a set of assuptions. I am only interested in obtaining V1 as a function of the exogenous parameters. I am using the following code: <...
1
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0answers
39 views

How to find solutions of a two-variable equation with discrete domains?

I have a two-variable function f[x_, y_] == 0, with a discrete domain for each variable, $x=\{1.5,\; 2.5,\; 3.5,\;4.5,\;5.5,\;\text{...},\infty \}$ and $y=\{0.1,\;...
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1answer
54 views

Root finding: Is there no bisection method root finder?

I am trying to find a root to an equation f[k,...]==0 numerically, where k is the variable I am solving for. Using both NSove as ...
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0answers
99 views

Is it possible to solve this equation analytically?

I have this equation, and I want to find an exact solution for $x$ in terms of $y$. I mean I want to obtain something like $x=f(y)$. Is it possible to solve this equation analytically by Mathematica? <...
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2answers
63 views

How to find non-trivial of a system of equation?

I have a system of four equations ...
5
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1answer
131 views

How can I reduce timing to solve this equation?

I am tring to solve equation $$\frac{2 \log (x y+2021)}{\log (2)}+4^{x+1}=2^{x y+2022}+\frac{2 \log (2 x+1)}{\log (2)},$$ where $x$, $y$ are integer numbers. I tried ...
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2answers
43 views

Evaluate with numbers from list

This code works: x=2 y/.Solve[y==x^2] Out[138]= 2 Out[139]= {4} So above I put number in variable x and getting the result of ...
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4answers
121 views

Is it possible to get a symbolic or numeric relation when solving a transcendental equation? [closed]

Here is the code. Solve[(1 - E^x + (3 x^2)/2)/(2 x) == a, x, Reals] Unfortunately, Mathematica told me that this system cannot be solved with the methods ...
2
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2answers
88 views

How can I solve $\coth (2 x )=x $? [duplicate]

I have this equation $$\coth (2 x )=x $$ and I want to solve it to find $x$. The methods Solve and Reduce do not work. Coth[2 x] == x
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0answers
38 views

How to deal with unknown variables in NSolve?

I am trying to solve these equations by using NSolve and want to plot $p1^{2}+p2^{2}$ v/s P0. But there is some problem, it is showing running... but not showing any error. I don't know where I am ...
1
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1answer
69 views

Why mathematica does not solve the equation $x\left \lfloor x \right \rfloor=10$ for $x$?

The equation $x\left \lfloor x \right \rfloor=10$ has a real solution, which is $x=\frac{10}{3}$. But when I type Solve[x*Floor[x] == 10, x] a message comes: "...
6
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1answer
159 views

How to solve system of PDE's with complicated initial and boundary conditions

I am trying to solve the Cavity problem given in Paper by Mansour et al. with a physical model . System of PDE and B.C are . How can I impose boundary conditions like this? Code ...

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