1. By Mrs. Muller

2. Key Vocabulary  Equation: mathematical sentence that has an equal sign, =.  Isolate: to get it alone  Variable: a letter representing an unknown amount.  Isolate the Variable: to get it alone on one side of the equation  Inverse Operations: Operations that undo each other

3. Solving the Equation  We have the equation: x+2=5, and we are asked to solve for x.  The first thing to do is remember that x+2=5 is an equation so both sides are equal to each other like on a scale. X+2X+2=5 X

4. Solving the Equation  What we are trying to do is to isolate the variable by getting it by itself.  Just looking at the scale, to do that we would have to get rid of the two cubes.  Now if you get rid of two cubes on the left of the scale you have to get rid of 2 on the right or the scale would be unbalanced.  X will be by itself then with 3 cubes on the right; meaning X=3 X+2X+2=5 X

5. Solving the Equation  Using just the equation is the same thing. What you do to one side, you must do to the other side to keep the equation balanced.  In order to do this you use the inverse operation (the opposite one) in order to undo the operation done to the variable in order to get the variable alone (isolated).  In this case we are looking at addition (+) and the opposite/inverse operation is subtraction (-); which makes sense since the opposite of a positive is a negative.

6. Solving Equations  Let’s look at an example of this:  15+g=120  The inverse operation of adding 15 in or being positive 15, is subtraction, so we will subtract 15 from both sides in order to keep the equation balanced.  15+g=120 -15 - 15 g= 105 15-15 is O and 0+g=g so just write g