Wednesday, December 2, 2009

Algebraic Translations

  • Translating English into algebra:
    1) Assign variables
        - Try to minimize the number of variables
        - Make use of a relationship given in the problem.
    2) Write equations
    3) Solve algebraically
    4) Evaluate the algebraic solution in the context of the problem - make sure you answer the question asked
  • You can check your translations with easy numbers.
  • Write an unknown percent as a variable divided by 100
  • Translate bulk discounts and similar relationships carefully
  • When a problem involves several quantities and multiple relationships, it is often a good idea to make a chart or a table to organize the information, i.e. age problems:
    - Put people in rows and times in columns.
    - Use variables to indicate the age of each person now, fill other columns by adding or subtracting time from the now column.
    - Write equations that relate the individuals' ages together
  • In a typical Price-Quantity problem, you have two relationships:
    - the quantities sum to a total
    - the monetary values sum to a total
  • Look out for hidden constraints (i.e. whole number, positive)
    - Think about what is being measured or counted and whether a hidden constraint applies.
    - To solve algebra problems that have integer constraints, test possible values systematically in a table.
    - When all quantities are positive in a problem, certain algebraic manipulations are safe to perform: 1) dropping negative solutions of equations; 2) dropping negative possibilities with inequalities (see MGMAT WT p21)

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