A Variable is a letter representing a number.

 x = 3

2 + x = 2 + 3 = 5

  x = 8

2x 4 =4

16 4=4

      To solve one-step equations use the inverse operation.
      Addition is the inverse of subtraction and vice versa.
      Multiplication is the inverse of division and vice versa.

Variables are used when the formula stays the same but the numbers change.

Click HERE to practice.


    Once you have solved the equation, use a formal check to make sure your solution is correct.
 

 

Example: x + 4 = -12
The inverse operation is subtraction of 4 from both sides.
      x + 4 – 4 = -12 –4
      x = -16
          ?
      Check: -16 + 4 = -12
      -12 = -12

 

Example: d – 8 = -15
The inverse operation is addition of 8 to both sides.
      d – 8 + 8 = -15 + 8
      d = -7
            ?
      Check: -7 – 8 = -15
      -15 = -15

   

Example: -4c = 44
The inverse operation is division of each side by -4.
      -4c (-4) = 44(-4)
      c = -11
          ?
      Check: -4 x –11 = 44
      44 = 44

Example: F8 = -4
The inverse operation is multiplication of each side by 8.
      8 x f8 = -4 x 8
      f = -32
          ?
      Check: -328 = -4
      -4 = -4

     
Example: Jack Nickles is behind in a golf tournament. He currently is at – 1. The leader John Weekly is at – 8. What score does Jack need to win the tournament? Write an equation to represent this problem and then solve it.

     ANSWER: j + -1 = -8
    The inverse operation is
    subtraction of – 1 from
    both sides.
      j + - 1 – (-1) = -8 – (-1)
      j = -7
          ?
      Check: -7 + -1 = -8
      -8 = -8

Alpha | Interactive Problem with Cookieman