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How to Write an Algebra Equation

In algebra, an algebraic equation translates values from a word problem into a mathematical statement. An equation can contain a combination of constants, variables, exponents and a variety of mathematical operational signs. An equal sign links the two sides of the equation and states that both mathematical sentences have the same numerical value. Students use mathematical equations to translate literal values into numerical ones to evaluate math problems. After the equation is formed, students use basic operations to isolate the variable for a solution.

Instructions

  1. Understanding the Process

    • 1

      Read the story problem: "The sum of two consecutive odd numbers equals twenty-four. What are both of the numbers?"

    • 2

      Translate the facts from the word problem into mathematical values. Let x represent the first of the numbers and use x + 2 to represent the second of the consecutive numbers, remember to use + 2 because the problem calls for two consecutive odd numbers.

    • 3

      Write an algebraic equation to include the rest of the values from the word problem: x + (x + 2) = 24.

    • 4

      Combine like terms: 2x + 2 = 24. Subtract 2 from both sides of the equation: 2x = 22. Divide both sides of the equation by 2: x = 11. Therefore, the first number is 11 and after adding two, the second number is 13. Check the math for validity: 11 + 13 = 24, which is a true statement.

    Practice

    • 5

      Write an algebraic equation from the following story problem: "A 21-foot board is cut into two pieces in such a way that the first piece is 3 feet shorter than the second. What are the lengths of each piece?"

    • 6

      Convert the facts into mathematical value. Let x represent the second board and x - 3 represent the first board. Set the facts equal to 21 because the board is 21 feet long: x + (x - 3) = 21. After following the correct operations, you should find that the first board is nine feet long and the second is 12.

    • 7

      Write an algebraic equation from the following story problem: "Two squared plus a number has the same value as two plus six. What is the number?"

    • 8

      Translate the literal values to mathematical ones using x to represent the unknown number: 2^2 + x = 2 + 6. The equation simplifies to 4 + x = 8 and after following the basic operations, you should find that the solution is x = 4.

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