How to solve system of equations with 3 variables calculator

Simultaneous Linear Equations Solver for Three Variables

This calculator calculates for the three unknown variables in three linear equations. Just put in the coefficients of the variables and the equivalent sum to the right of the equation. Please fill in all input boxes. If an equation does not include a certain variable put zero as the coefficient for that variable. The equations are expressed a little differently than you would normally see them. For example, x+y+z=44 would be expressed as 1x+1y+1z=44 which is still mathematically correct. 2x-3y+5z=12 would be expressed as 2x + -3y + 5z = 12 which is also mathematically correct. A minus operator is replaced by a plus operator and a negative coefficient of a variable. Coefficients to variables can be negative numbers. This method of inputting coefficients is in accordance with the rules of matrix algebra. The number of decimal places in the results can be specified.

Equations
Equation 1: X + Y + Z =
Equation 2: X + Y + Z =
Equation 3: X + Y + Z =
Decimal Places

This solver (calculator) will try to solve a system of 2, 3, 4, 5 equations of any kind, including polynomial, rational, irrational, exponential, logarithmic, trigonometric, hyperbolic, absolute value, etc. It can find both the real and the complex solutions. To solve a system of linear equations with steps, use the system of linear equations calculator.

Enter a system of equations:

Comma-separated, for example, x+2y=5,3x+5y=14.

Solve for (comma-separated):

Leave empty for automatic determination, or specify variables like x,y.

If the calculator did not compute something or you have identified an error, or you have a suggestion/feedback, please write it in the comments below.

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System of Equations Calculator

Step-by-step calculator for systems of equations.

What do you want to calculate?

Systems of Equations Calculator is a calculator that solves systems of equations step-by-step.

Example (Click to view)

x+y=7; x+2y=11

Try it now

  • Enter your equations in the boxes above, and press Calculate!
  • Or click the example.

About MathPapa

Learn how to use the Algebra Calculator to solve systems of equations.

Example Problem

Solve the following system of equations:
x+y=7, x+2y=11

How to Solve the System of Equations in Algebra Calculator

First go to the Algebra Calculator main page.

Type the following:

  1. The first equation x+y=7
  2. Then a comma ,
  3. Then the second equation x+2y=11

Try it now: x+y=7, x+2y=11

Clickable Demo

Try entering x+y=7, x+2y=11 into the text box.

How to solve system of equations with 3 variables calculator

After you enter the system of equations, Algebra Calculator will solve the system x+y=7, x+2y=11 to get x=3 and y=4.

How to solve system of equations with 3 variables calculator

More Examples

Here are more examples of how to solve systems of equations in Algebra Calculator. Feel free to try them now.

  • Solve y=x+3, y=2x+1: y=x+3, y=2x+1
  • Solve 2x+3y=5, x+y=4: 2x+3y=5, x+y=4

Need Help?

Please feel free to Ask MathPapa if you run into problems.

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  • 3 x 3 Systems Solver

This calculator solves system of three equations with three unknowns (3x3 system). The calculator will use the Gaussian elimination or Cramer's rule to generate a step by step explanation.

examples

Solve by using Gaussian elimination: $$ \begin{aligned} x + 2y - z & = 2 \\[2ex] x - y + 2z & = 5 \\[2ex] 2x + 2y + 2z & = 12 \end{aligned} $$

Solve by using Cramer's rule $$ \begin{aligned} -x + \frac{2}{3}y - 2z & = 2 \\[2ex] 5x + 7y - 5z & = 6 \\[2ex] \frac{1}{4}x + y - \frac{1}{2}z & = 2 \end{aligned} $$

About Cramer's rule

This calculator uses Cramer's rule to solve systems of three equations with three unknowns. The Cramer's rule can be stated as follows:

Given the system:

$$ \begin{aligned} a_1x + b_1y + c_1z = d_1 \\ a_2x + b_2y + c_2z = d_2 \\ a_3x + b_3y + c_3z = d_3 \end{aligned} $$

with

$$ D = \left|\begin{array}{ccc} a_1 & b_1 & c_1 \\ a_2 & b_2 & c_2 \\ a_3 & b_3 & c_3 \\ \end{array}\right| \ne 0 $$ $$ D_x = \left|\begin{array}{ccc} d_1 & b_1 & c_1 \\ d_2 & b_2 & c_2 \\ d_3 & b_3 & c_3 \\ \end{array}\right| $$ $$ D_y = \left|\begin{array}{ccc} a_1 & d_1 & c_1 \\ a_2 & d_2 & c_2 \\ a_3 & d_3 & c_3 \\ \end{array}\right| $$ $$ D_z = \left|\begin{array}{ccc} a_1 & b_1 & d_1 \\ a_2 & b_2 & d_2 \\ a_3 & b_3 & d_3 \\ \end{array}\right| $$

then the solution of this system is:

$$ x = \frac{D_x}{D} $$ $$ y = \frac{D_y}{D} $$ $$ z = \frac{D_z}{D} $$

Example: Solve the system of equations using Cramer's rule

$$ \begin{aligned} 4x + 5y -2z= & -14 \\ 7x - ~y +2z= & 42 \\ 3x + ~y + 4z= & 28 \\ \end{aligned} $$

Solution: First we compute $ D,~ D_x,~ D_y $ and $ D_z $.

$$ \begin{aligned} & D~~ = \left|\begin{array}{ccc} {\color{blue}{4}} & {\color{red}{~5}} & {\color{green}{-2}} \\ {\color{blue}{7}} & {\color{red}{-1}} & {\color{green}{~2}} \\ {\color{blue}{3}} & {\color{red}{~1}} & {\color{green}{~4}} \end{array}\right| = -16 + 30 - 14 - 6 - 8 - 140 = -154\\ & D_x = \left|\begin{array}{ccc} -14 & {\color{red}{~5}} & {\color{green}{-2}} \\ ~42 & {\color{red}{-1}} & {\color{green}{~2}} \\ ~28 & {\color{red}{1}} & {\color{green}{~4}} \end{array}\right| = 56 + 280 - 84 - 56 + 28 - 840 = -616\\ & D_y = \left|\begin{array}{ccc} {\color{blue}{4}} & -14 & {\color{green}{-2}} \\ {\color{blue}{7}} & ~42 & {\color{green}{~2}} \\ {\color{blue}{3}} & ~28 & {\color{green}{~4}} \end{array}\right| = 672 - 84 - 392 + 252 - 224 + 392 = 616\\ & D_Z = \left|\begin{array}{ccc} {\color{blue}{4}} & {\color{red}{~5}} & -14 \\ {\color{blue}{7}} & {\color{red}{-1}} & ~42 \\ {\color{blue}{3}} & {\color{red}{~1}} & ~28 \end{array}\right| = -112 + 630 - 98 - 42 - 168 - 980 = -770\\ \end{aligned} $$

Therefore,

$$ \begin{aligned} & x = \frac{D_x}{D} = \frac{-616}{-154} = 4 \\ & y = \frac{D_y}{D} = \frac{ 616}{-154} = -4 \\ & z = \frac{D_z}{D} = \frac{-770}{-154} = 5 \end{aligned} $$

Note: You can check the solution using above calculator

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How do you solve a system of equation with 3 variables?

To solve a system of three equations in three variables, we will be using the linear combination method. This time we will take two equations at a time to eliminate one variable and using the resulting equations in two variables to eliminate a second variable and solve for the third.