Rules of Solving Equations (Algebra & Graphing)

 

Rules for Algebraic solution

 

Rules and example for 3x +12 > 20 and –4x +15 < 35:

  1. Move all terms containing variables to the left of the inequality.
  2. Move all numbers to the right of the inequality.

3x + 12 > 20                -4x +15 < 35

     -12     -12                     -15     -15

3x > 8                          -4x < 20

  1. Divide both sides by coefficient (slope) of x.  If you are dividing by a negative number, be sure to reverse the inequality sign

3x / 3 > 8/3                  -4x / -4 < 20 / -4

x > 8/3 or 2 2/3            x > -5

  1. Write the answer and compare to the graph.

 

Rules for class

 

Required for all classes:

  1. Put into two equations:

y = 3x + 12                  y = -4x +15

y = 20                          y = 35

  1. Create and use table
  2. Determine the values for x you will use (do not think you need to count by 1).
  3. Calculate the values of y, based on x.  Make sure you are incrementing in a way large enough that y increases quickly enough to cross the second value of y in these two equations.  Make sure you are going in the correct direction as well as a large enough value.
  4. Continue calculations of y until value crosses or equals the second y value.

 

Assignment

 

Pg. 6-7, problems 1, 2, 7-10