# equation-solving's questions - English 1answer

3.383 equation-solving questions.

### Finding series expansion of solution of algebraic equation

I have the following algebraic equation ...

### How to automatically select solutions from a set of solutions given by Solve?

1 answers, 35 views equation-solving filtering
I have a function of trigonometric functions which must be equated to zero in order to obtain the appropriate results. This is done in the following fashion: ...

### Can't solve InfiniteLine example: not a quantified system of equations [on hold]

I'm trying to complete an example from https://reference.wolfram.com/language/ref/InfiniteLine.html Find the intersection of InfiniteLine[{0,0},{1,1}] and InfiniteLine[{{0,1},{1,0}}]: But when I ...

### 3 How do I find a function to fit these criteria?

I want to find a smooth continuous function f[x] that satisfies the following for real values of x: ...

### 5 How to find the numbers $a$, $b$, $c$, $d$ so that the equation has four distinct integral solutions?

I want to find the numbers $a$, $b$, $c$, $d$ so that the equation $$x^4 + a x^3 + b x^2 + c x + d=0,$$ where $d = \dfrac{c^2}{a^2}$ has four distinct integral solutions. With Maple, I found some ...

### 3 How to solve numerically an equation which contains numerical integration?

F1[x_] := NIntegrate[E^Sin[y x], {y, 0, 1}] F2[x_] := Log[x] NSolve[F1[x] == F2[x], x]I want to solve the equation, but Mathematica don't solve it. ...

### 2 Help needed to make NIntegrate Converge

I have the following notebook (trying to caclulate the pull-in voltage of a structure): ...

### Finding a numerical solution and plotting it over a wide range

My problem is that I am trying to find a Numerical solution to a function of the form f(x,c)== K for x for some given values of c, K, and plot this function over a wide range of values of c. My ...

### Problem with Solve Function: It gives wrong solution!

I tried to run the codes ...

### 3 Solving a non-linear ODE system with ParametricNDSolveValue

I'm trying to solve a non linear ODE numerically with ParametricNDSolve, but as far as I got is shown below. My problem is to set the find root correctly. What I ...

### 1 How to solve a stiff non-linear differential equation?

I am having trouble solving the following differential equation, where $\theta(x)$ is a phase, \frac{d\theta}{dx} + \sin^2 \left[ \theta(x) \right] + K^2(x) \cos^2 \left[\theta(x) \...

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### Solve/Simplify an Equation that involves multiple variables for one variable e.g. x

I am new at Mathematica and have very basic knowledge about it. I want to solve the following equation for variable x in Mathemtica. ...

### Calculate value of expressions based on solution of given linear equations

I have these three equations:1/X + 1/Y == 1/15; 1/Y + 1/Z == 1/20; 1/Z + 1/X == 1/25;I want to calculate the value of expression: ...

### 1 How to represent in a 3D graph the set of solutions to this system of inequalities?

I am studying this piecewise function: ...

### Solve a Second-Order Differential Equation Numerically, with boundary conditions?

Below is an ODE with BC define as x[R]=0, x'[0]=0, x'[R]=0 and parameter n. The ODE is stiff at certain data, and I need to see the behavior of x' and x for given ...

### How to solve this 4th degree polynomial equation with complex coefficients numerically in Mathematica?

3 answers, 78 views equation-solving polynomials
I have a polynomial equation: $-(a-ib)e^{(4\pi i/3)}(\sqrt{2}i+x^3/\sqrt{3})x- (a+ib) e^{(2\pi i/3)}(\sqrt{2}ix^3+1/\sqrt{3})=0$ (which in code is): ...

### Trouble with NSolve

I have a fairly simple program that yields puzzling output. The program is ...

### How to speed up this calculation regarding the normal distribution?

This calculation takes a very long time! Why? How can I improve it? Thanks! ...

### 1 PDE in 3D: Specification boundary condition at infinity

I'm trying to solve the Schrodinger equation and having difficulties to define a limitless region because the problem has the Dirichlet conditions at infinity. Maybe I don't need such a region and ...

### 2 Solving an equation with vector coefficients

2 answers, 175 views equation-solving tensors algebra
I want to solve $(ct)^2 = d(t)\cdot d(t)$ for $t$, where $d(t) = \frac{1}{2}at^2 + vt + r$ Where$a, v$, and $r$ are all 3-dimensional vectors in Cartesian coordinates. How can I do this?

### 1 Help For Solving Complicated Function

I have a piece-wise defined function: ...

### 3 Schrödinger equation for a hydrogen atom and lack of memory

I'm trying to solve the Schrödinger equation for a hydrogen atom in the Cartesian coordinate system. This is my code ...

### 5 How to solve this equation numerically or analytically

In the paper, entitled: A Closed Form Solution for the Pull-in Voltage of the Micro Bridge (Link to PDF: https://pdfs.semanticscholar.org/0d31/33707b1243f6b4e3344c4fa19b831b010b8b.pdf) ... the ...

### 1 Delay difference equation

How can I correctly specify and solve a system of delay difference equations in mathematica similar to NDSolve with regard to delay differential equations? For example if I want to "see" the values ...

### 2 Problem with NSolve Speed

I have a very complicated function but only of 1 variable. I want to find the first value for which that function is zero. Mathematica can easily plot it: ...

### Plotting numerical solution of the system when parameters change

0 answers, 25 views plotting equation-solving