# Tagged Questions

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

213 views

### Strange behaviour of NotElement in Reduce

Bug introduced in 8.0 or earlier and persisting through 10.4 or later Confirmed, as bug, by WRI: [CASE:3527549] I have observed curious behaviour on domains supplied to ...
109 views

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### How to find the value of a variable using solution of Simultaneous equations? [closed]

I have to find the value of p where p=a1*x+b2*y; using the solution of the equation ...
112 views

### How do I find the analytical roots of this polynomial? [closed]

I want to find the analytical roots of this polynomial - x - a^3*x*(a^2*x*(a*x*(x - 1) + 1)*(x - 1) + 1)*(a*x*(x - 1) + 1)*(x - 1) ...
39 views

### Transform system of equations while leaving solution set invariant?

Consider the example system of equations syst==res where syst={x + 2 y + 3 x y, 1 + 4 x + y}; res={0 , 0}; Solving for the ...
48 views

### Solve Two Functions In Three Variables and use ContourPlot [closed]

I am solving this system in mathematica ...
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### Simplify doesn't simplify multiple conditions from Reduce

Consider the following simple example where I try to solve an equation and then apply a bounded interval to find the right result out of an infinite amount of solutions: ...
128 views

### FindRoot of interpolating function from NDSolve

I am having issues finding the root of an interpolating function obtained from NDSolve. For example: ...
239 views

### Simultaneous equations—classify the solution set as finite, infinite, or none [duplicate]

How do I find the values of $b$ and $c$ for the equations $x + 5 y = 4$ and $2 x + by = c$ with a unique solution, an infinite set of solutions and no solutions with Mathematica?
60 views

### Solving a simple trigonometric equation in a range

I would like to solve a simple trigonometric equation, for example $\sin\theta=\frac{1}{2},$ but Solve gives the single solution obtained by using the inverse ...
114 views

### Finding all complex polynomial roots in a specified range efficiently

I need to find the roots of a rational polynomial that are near i. In the following code, I try that two different ways. First, I use a constraint to only find roots in the right region. Second, I ...
157 views

### How do I plot this (x^3 - 2*x)^Ln[x]? [closed]

y=(x^3 - 2*x)^Ln[x] I'm totally clueless. I tried with y=e^(Ln[x] Ln[-2 x + x^3]) by Ln-ing on both sides but there is ...
52 views

### Strange behavior when solving absolute value equations

Try this: Solve[Abs[x/2 - 1/3] == 1, x] Produces this answer: (* {{x -> -(4/3)}, {x -> 8/3}} *) Now try this: ...
89 views

### Help numerically solve this non-linear PDE with singularity

I have trouble finding a numerical solution to the partial differential equation below. It seems to be a singularity in the solution somewhere, so I searched online and found that it is suggested to ...
432 views

### Is there any predictor-corrector method in Mathematica for solving nonlinear system of algebraic equations?

The FindRoot Function in Matheatica can easily be used to solve systems of nonlinear algebraic equations. But, I want to solve a system of nonlinear equations with variations of some parameters. ...
103 views

### Solving equations with subscripted variables

A student of mine tried: Solve[1/R == 1/Subscript[R, 1] + 1/Subscript[R, 2], R] which did not work. We then tried: ...
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### Combining two NDsolves results in “The search has encountered a complex value…” and no solution

So far I used to seperate NDsolves to solve a system of coupled differential equations, where the first NDsolve yields the Boundary conditions for the second NDsolve ...
445 views

### Solving complex equations with variable exponents

How would I go about solving $(1+i)^n = (1+\sqrt{3}i)^m$ for integer $m$ and $n$? I have tried ...
207 views

### Using Solve to solve the equation $x^{1/3}=-1$

I am curious why this command returned no answers: Solve[x^(1/3) == -1, x] Gives this output: (* {} *) I was able to get ...
263 views

### Number of solutions for inequality

Please explain me how can I calculate a number of possible solutions for such inequality and obtain those values: 3x + 7y + z <= 198 where ...
71 views

### Integrate over FindRoot solutions

I have a function of bivariate normal PDF and its marginals defined as ...
66 views

### Eliminating one function from non-linear PDE

Is there any solution to eliminate function p[x,y] from these two equations which are equal to zero (diff1=0 and diff2=0) where c and d are constants. I need one equation where should figure just w[x,...