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Solving equations with one unknown

Solving equations with one unknown

Solving equations with one unknown involves determining the value of a variable that makes an equation true. The general steps include:

  1. Identifying the equation: typically in the form ax+b=cax + b = c, where a,b,a, b, and cc are constants, and xx is the unknown.

  2. Isolating the variable: This usually involves backwards operations to remove constants or coefficients. For example:

    • Subtract bb from both sides: ax=cbax = c - b
    • Divide both sides by aa: x=cbax = \frac{c - b}{a}
  3. Verifying the solution: Substitute the found value of xx back into the original equation to ensure both sides are equal.

  4. Understanding multiple solutions: Some equations may have no solution, one solution, or infinitely many depending on their structure.

Overall, the process emphasizes balancing the equation using inverse operations to solve for the unknown.

Part 1: Equations with parentheses

When an equation such as -9 - (9x - 6) = 3(4x + 6) has parentheses, we can distribute without changing the value of each side. Then combine like terms. Next, we move all the x-terms to one side and the constants to the other. Finally, we solve for x. 

Here are the key points to learn when studying "Equations with parentheses":

  1. Understanding Parentheses: Recognize that parentheses indicate which operations should be performed first. This is crucial for simplifying expressions correctly.

  2. Order of Operations: Familiarize yourself with the order of operations (PEMDAS/BODMAS) where Parentheses/Brackets come first, followed by Exponents/Orders, Multiplication and Division (left to right), and Addition and Subtraction (left to right).

  3. Distributing: Learn how to use the distributive property to eliminate parentheses. This involves multiplying the term outside the parentheses by each term inside.

  4. Combining Like Terms: After distribution, combine any like terms to simplify the equation.

  5. Solving for Variables: When isolating the variable, reverse operations systematically while maintaining the balance of the equation.

  6. Checking Solutions: Always substitute your solution back into the original equation to verify correctness.

  7. Multi-step Equations: Practice solving equations that require multiple steps, including distributing, combining like terms, and isolating the variable.

By mastering these concepts, you will effectively handle equations with parentheses.

Part 2: Number of solutions to equations

A linear equation could have exactly 1, 0, or infinite solutions. If we can solve the equation and get something like x=b where b is a specific number, then we have one solution. If we end up with a statement that's always false, like 3=5, then there's no solution. If we end up with a statement that's always true, like 5=5, then there are infinite solutions.

When studying the "Number of solutions to equations," focus on the following key points:

  1. Types of Equations:

    • Linear equations
    • Quadratic equations
    • Polynomial equations (higher degree)
    • Systems of equations
  2. Methods of Finding Solutions:

    • Graphical method
    • Algebraic methods (factoring, using formulas)
    • Substitution and elimination (for systems)
  3. Count of Solutions:

    • Unique solution (one solution)
    • No solution (inconsistent system)
    • Infinite solutions (dependent system)
  4. Discriminant in Quadratics:

    • Understanding the discriminant (D = b² - 4ac)
    • Interpreting D:
      • D > 0: Two distinct real solutions
      • D = 0: One real solution (double root)
      • D < 0: No real solutions
  5. Real vs. Complex Solutions:

    • Identification of real solutions versus complex (imaginary) solutions, particularly in higher-degree polynomials.
  6. Special Cases:

    • Identifying special conditions like parallel lines, coincident lines, or specific roots in polynomial equations.
  7. Application of the Fundamental Theorem of Algebra:

    • Every polynomial of degree n has exactly n roots (considering multiplicity and complex solutions).

By understanding and mastering these key points, you will be well-equipped to analyze and determine the number of solutions to various types of equations.

Part 3: Worked example: number of solutions to equations

Sal attempts to solve 8(3x + 10) = 28x - 14 - 4x only to find that the equation has no solution.

When studying "Worked Example: Number of Solutions to Equations," focus on these key points:

  1. Identifying the Type of Equation: Determine if the equation is linear, quadratic, polynomial, or involves absolute values, as the type influences the number of solutions.

  2. Analyzing Degree: For polynomial equations, the degree affects the maximum number of solutions—an nn degree polynomial can have up to nn solutions.

  3. Graphical Interpretation: Visualizing equations can help in understanding solutions—look at the intersection points between graphs of functions.

  4. Use of Discriminants: For quadratic equations, using the discriminant (b24acb^2 - 4ac) helps determine the number of real solutions (two, one, or none).

  5. Consideration of Complex Solutions: Some equations may have complex solutions, which is particularly relevant for polynomials and higher-degree equations.

  6. Special Cases: Recognize special cases where equations may simplify (e.g., identities leading to infinite solutions or contradictions resulting in no solutions).

  7. Estimating Solutions with Numerical Methods: Familiarize yourself with numerical methods (like the Newton-Raphson method) for approximating solutions when analytical methods are difficult.

By focusing on these areas, you'll gain a comprehensive understanding of how to analyze and determine the number of solutions for various equations.