Solve Command

Commands Solve and Solutions solve an equation or a system of equations over the real numbers symbolically. To solve equations numerically, use the NSolve Command. For solving equations in complex numbers see CSolve Command.

Solve( <Equation in x> )

Solves a given equation for the main variable and returns a list of all solutions.

Solve(x^2 = 4x) yields {x = 4, x = 0}, the solutions of x2 = 4x.

CAS Syntax

The following commands are only available in the Menu view cas.svg CAS View.

Solve( <Equation>, <Variable> )

Solves an equation for a given unknown variable and returns a list of all solutions.

Solve(x * a^2 = 4a, a) yields {\(a = \frac{4}{x}, a = 0\)}.

Solve( <Equation in x>, <Assumption> )

Solves an equation x, conditional on the assumption

Solve(x^2=1, x>0) yields \({x = 1}\)

Solve( <List of Equations>, <List of Variables> )

Solves a set of equations for a given set of unknown variables and returns a list of all solutions.

  • Solve({x = 4 x + y , y + x = 2}, {x, y}) yields ( x = -1, y = 3 )

  • Solve({2a^2 + 5a + 3 = b, a + b = 3}, {a, b}) yields {{a = 0, b = 3}, {a = -3, b = 6}}.

Solve( <Equation>, <Variable> , <List of assumptions>)

Solves an equation for a given unknown variable with the list of assumptions and returns a list of all solutions.

  • Solve(u *x < a,x, u>0) yields {x < a / u}, the solution of u *x < a assuming that u>0

  • Solve(u *x < a,x, {u<0, a<0}) yields {x > a / u}.

Solve( <List of Parametric Equations>, <List of Variables> )

Solves a set of parametric equations for a given set of unknown variables and returns a list of all solutions.

  • Solve({(x, y) = (3, 2) + t*(5, 1), (x, y) = (4, 1) + s*(1, -1)}, {x, y, t, s}) yields {{x = 3, y = 2, t = 0, s = -1}}.

  • The right hand side of equations (in any of the above syntaxes) can be omitted. If the right hand side is missing, it is treated as 0.

  • Sometimes you need to do some manipulation to allow the automatic solver to work, for example Solve(TrigExpand(sin(5/4 π + x) - cos(x - 3/4 π) = sqrt(6) * cos(x) - sqrt(2))).

  • For piecewise-defined functions, you will need to use NSolve