Linear systems

Notes

  • Two or more equations with a link.
  • Solution to a system is ordered pair(s) that satisfy all equations.
    • Shown linked by a brace
  • Solve by graphing, substitution or exclusion
  • A system can be classified:
    • Dependent - all solutions are the same, infinite solutions to the system
    • Independent - each has it's own solutions
    • Consistent - there's a solution to the system
    • Inconsistent - there's no solution to the system
Lines Intersecting Parallel Coincident
Number of solutions 1 point No solution Infinitely many
Consistent/inconsistent Consistent Inconsistent Consistent
Dependent/ independent Independent Independent Dependent

Solve by graphing

Simply get the equations into slope-intercept form: y=mx+b , graph them and and see where or if the lines intersect.

Solve a system of equations by substitution

  • See paper notes for detail and examples
  1. Step 1.  Solve one of the equations for either variable.
  2. Step 2.  Substitute the expression from Step 1 into the other equation.
  3. Step 3.  Solve the resulting equation.
  4. Step 4.  Substitute the solution in Step 3 into either of the original equations to find the other variable.
  5. Step 5.  Write the solution as an ordered pair.
  6. Step 6.  Check that the ordered pair is a solution to both original equations.

Solve a system of equations by elimination

  • See paper notes for detail and examples
  1. Write both equations in standard form
  2. Transform the coefficients of one pair of variable terms into opposites
  3. Add the two left sides of the equations together, set this equal to the sum of the two right sides of the equations
  4. Solve the linear equation in one variable
  5. Find the other unknown using substitution
  6. Check

Apply linear systems

  1. Read the problem, get a clear understanding of the objective
  2. Assign a variable to represent each unknown
  3. Write two equations using both variables
  4. Solve the linear system
  5. State the answer using a nice clear sentence
  6. Check the result by reading back through the problem

Systems of linear inequalities