In order for this method to work, your equations must be linear in the form Ax+By+Cz...=F. For equations in slope-intercept form (y=mx+b), just plug in the constants into this formula: y-mx=b. For others, get all of your variables onto the left side and your constants on the right and simplify. Remember which order your variables were in for when you interpret the final matrix.
 On the TI83, the keystrokes are "2nd" then "x-1" to enter the matrix screen. On other calculators, look for the word "matrix." Move your cursor right until you reach the edit screen. Scroll down to a matrix you aren't using and press enter.
 Look at the top. Your cursor should be over a number, then there should be an "x" sign followed by another number. The first number corresponds to the number of rows in the matrix and the second number corresponds to the number of columns. Type in the number of variables for the rows and type in the number of variables plus 1 for the columns. Press enter after typing in each number. Once you've entered the row and column numbers, you will be taken to the data part. At the bottom, the "coordinates" of the cell you are entering will be shown. The first number corresponds to the row number and the second to the column number. Make sure that anything with a 1 in the rows column should be for the first equation, anything with a 2 is for the second, etc. and that anything with a 1 should be for the first variable, anything with a 2 is for the second variable etc. Be sure all coefficients for a variable are in the same column. To enter the data, just type in the first coefficient (a coefficient is the number before the variable) of the first equation, then the second coefficient, then the third coefficient etc. The last number in the row should be the constant on the right side of the equation. After typing in each number press enter. At the end of a row, press enter to be taken to the next row. Type in the equations in their corresponding rows in this manner.
 Quit out of the editor. On the TI83 press "2nd" then "delete." Use the quit button instead of pressing clear or you might end up deleting the data cell your cursor was over. From the home screen, go back to the matrix screen (not the editor), and move your cursor to the right until you reach the "Math" menu. Scroll down to "rref" (be sure you don't go to "ref" by mistake) and press enter. Go to the matrix screen again, but this time just scroll down to the matrix you put your data into and press enter. Your home screen should say "rref(." Press enter to get the resultant matrix. Your answer is in the column farthest to the right. The top number corresponds to the first variable, the next number down corresponds to the second variable, etc.
Convert the equations into standard form.
Go to the matrix editor.
Enter your data.
Find the solution.
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