Mathematics for GIS Professionals

Process for Solving Linear Equations

Process for Solving Linear Equations


  1. If the equation contains any fractions use the least common denominator to clear the fractions.  We will do this by multiplying both sides of the equation by the LCD.

    Also, if there are variables in the denominators of the fractions identify values of the variable which will give division by zero as we will need to avoid these values in our solution.

  2. Simplify both sides of the equation.  This means clearing out any parenthesis, and combining like terms.
  3. Use the first two facts above to get all terms with the variable in them on one side of the equations (combining into a single term of course) and all constants on the other side.
  4. If the coefficient of the variable is not a one use the third or fourth fact above (this will depend on just what the number is) to make the coefficient a one.

    Note that we usually just divide both sides of the equation by the coefficient if it is an integer or multiply both sides of the equation by the reciprocal of the coefficient if it is a fraction.

  5. VERIFY YOUR ANSWER!  This is the final step and the most often skipped step, yet it is probably the most important step in the process.  With this step you can know whether or not you got the correct answer long before your instructor ever looks at it.  We verify the answer by plugging the results from the previous steps into the original equation.  It is very important to plug into the original equation since you may have made a mistake in the very first step that led you to an incorrect answer.

    Also, if there were fractions in the problem and there were values of the variable that give division by zero (recall the first step…) it is important to make sure that one of these values didn’t end up in the solution set.  It is possible, as we’ll see in an example, to have these values show up in the solution set.

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