The Math Property of Equality

When you first learned about the math property of equality in elementary school, the symbol was used to signify this is the answer.

Here is an example of how the equal sign is used in elementary school

Old Use: 



But things are about to change...


In the figure below, you see a set of hands each containing $0.25.  The left hand has a quarter, and the right hand has 2 dimes and a nickel.  Both sides have different coins, but equal money

New Use:    $0.25 = $0.25!  

Equality says that I can perform an operation (add, subtract, multiply divide) on my equation as long as I do the same thing to both sides.  Watch how I add $0.01 to each hand...

  I now added one penny to each side of the equation.  Because I did the same thing to both hands, they are still equal.  $0.26 = $0.26!

Using the Math Property of Equality for Equations

In the illustration above, we used the property of equality by adding a penny to each side of our equation.

Let's take a look at a few examples of how we can use the property to solve equations....














The properties demonstrated above are known as the addition property, the subtraction property, the division property, and the multiplication property. They all are possible because of the equal sign.


Additional Information

Remember, the math property of equality says that you can perform an operation to an equation, as long as you do the same thing on both sides!

You may want to look at how to solve a linear equation - in this page we will look at two step equations and go more in depth about the four properties above.

Return to other pre-algebra help topics.

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