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You solve simultaneous equations involving negatives the same way you solve simultaneous equations not involving negatives. You subtract an appropriately scaled version of one from the other in order to cancel the terms of one variable, solving for the other variable. Remember that multiplying by -1 will reverse the signs, so that can be a trick to being able to visualize the subtraction. An example...

3x - 2y = 7

4x + 4y = -3

Multiply the first equation by -2 and solve for x...

-6x + 4y = -14

4x + 4y = -3

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-10x = -11

x = 1.1

Backsubstitute and solve for y

3x - 2y = 7

3.3 - 2y = 7

-2y = 3.7

y = -1.85

Its just a matter of keeping the signs straight and remembering that subtracting a minus means to add. You can also add the equations instead of subtracting, if it seems that would also cancel a term.

Q: How do you solve simultaneous equations that include negatives?

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Simultaneous equations are where you have multiple equations, often coupled with multiple variables. An example would be x+y=2, x-y=2. To solve for x and y, both equations would have to be used simultaneously.

Can't be done unless you have another equation with the same x and y. Then you would solve for simultaneous equations.

The analytical method involves simultaneous equations but if you do not know that, draw graphs of the equations: with one variable represented per axis. The solution, if any, is where the graphs meet.

You cannot work a simultaneous equation. You require a system of equations. How you solve them depends on their nature: two or more linear equations are relatively easy to solve by eliminating variables - one at a time and then substituting these values in the earlier equations. For systems of equations containing non-linear equations it is simpler to substitute for variable expression for one of the variables at the start and working towards the other variable(s).

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Its called Simultaneous Equations

Graphically might be the simplest answer.

solve systems of up to 29 simultaneous equations.

Parallel lines never meet and so parallel equations do not have any simultaneous solution.

Solve simultaneous equations of up to 29 variables.

Simultaneous equations are where you have multiple equations, often coupled with multiple variables. An example would be x+y=2, x-y=2. To solve for x and y, both equations would have to be used simultaneously.

The most common use for inverted matrices is to solve a set of simultaneous equations.

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Matrices are generally used to solve simultaneous equations. You use the co-efficient of the variables and arrange them in a matrix to solve them. To do so requires at least as many equation as there are variables. Other uses include vector calculations.

By substitution or elimination of one of the variables which usually involves simultaneous or straight line equations.

Can't be done unless you have another equation with the same x and y. Then you would solve for simultaneous equations.

Finding the point of intersection using graphs or geometry is the same as finding the algebraic solutions to the corresponding simultaneous equations.