8.3 Solve Equations with Variables and Constants on Both Sides

3 min readjune 25, 2024

Solving equations with variables and constants on both sides is a crucial skill in algebra. It involves isolating variables, combining , and performing operations on both sides of the to find solutions.

This process builds on basic equation-solving techniques, extending them to more complex scenarios. By mastering these methods, you'll be able to tackle a wide range of algebraic problems and develop a strong foundation for advanced math concepts.

Solving Equations with Variables and Constants on Both Sides

Equations with constants on both sides

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  • Isolate the on one side by performing the same operation on both sides of the equation
    • Subtract a from both sides if it is being added to the variable (x+3=7x + 3 = 7 becomes x=73x = 7 - 3)
    • Add a constant to both sides if it is being subtracted from the variable (x4=2x - 4 = 2 becomes x=2+4x = 2 + 4)
    • Divide both sides by a constant if it is multiplying the variable (3x=153x = 15 becomes x=15÷3x = 15 ÷ 3)
    • Multiply both sides by a constant if it is dividing the variable (x÷2=6x ÷ 2 = 6 becomes x=6×2x = 6 × 2)
  • Simplify the equation after performing the same operation on both sides to solve for the variable (x+2=8x + 2 = 8 becomes x=6x = 6)
  • The process of moving terms from one side of the equation to the other is called

Equations with variables on both sides

  • Get all variables on one side and all constants on the other side by choosing one side for the variables and performing the opposite operation on both sides
    • Subtract a variable from both sides if it is being added on one side (2x+3=x+72x + 3 = x + 7 becomes x+3=7x + 3 = 7)
    • Add a variable to both sides if it is being subtracted on one side (3xy=53x - y = 5 becomes 3x=5+y3x = 5 + y)
  • Combine like terms on each side of the equation after getting all variables on one side (2xx+3=72x - x + 3 = 7 becomes x+3=7x + 3 = 7)
  • Isolate the variable by performing the appropriate operation with the constants on the other side (x+3=7x + 3 = 7 becomes x=4x = 4)

Strategy for complex equation solving

  1. Simplify each side of the equation by combining like terms (3x2+4x=2x+3+5x13x - 2 + 4x = 2x + 3 + 5x - 1 becomes 7x2=7x+27x - 2 = 7x + 2)
  2. Get all variables on one side of the equation by performing the appropriate operation on both sides (7x2=7x+27x - 2 = 7x + 2 becomes 2=2-2 = 2)
  3. Get all constants on the other side of the equation by performing the appropriate operation on both sides (2=2-2 = 2 remains 2=2-2 = 2)
  4. Isolate the variable by performing the appropriate operation with the constants (2=2-2 = 2 becomes 2=22 = -2 by dividing both sides by -1)
  5. Determine the , which includes all values that satisfy the equation

Like terms in linear equations

  • Combine terms that have the same variable raised to the same power by adding or subtracting their coefficients (3x+2yx+4y3x + 2y - x + 4y becomes 2x+6y2x + 6y)
    • 3x3x and x-x are like terms with coefficients 3 and -1
    • 2y2y and 4y4y are like terms with coefficients 2 and 4
  • Simplify complex linear equations by combining like terms on each side of the equation before solving for the variable (2x+3yx=5x2y+12x + 3y - x = 5x - 2y + 1 becomes x+3y=4x2y+1x + 3y = 4x - 2y + 1)

Algebraic Expressions and Identities

  • An is a combination of variables, numbers, and operations (e.g., 2x + 3y)
  • An is an equation that is true for all values of the variables involved
  • Algebraic expressions can be simplified by combining like terms and applying properties of operations
  • Identities can be used to simplify complex equations and solve problems more efficiently

Key Terms to Review (17)

Algebraic Expression: An algebraic expression is a mathematical phrase that combines variables, numbers, and operations to represent a value or relationship. It is a fundamental concept in algebra that allows for the representation and manipulation of quantities without specific numerical values.
Balancing Method: The balancing method is a systematic approach used to solve linear equations with variables and constants on both sides of the equation. It involves performing a series of algebraic operations to isolate the variable and find the solution that satisfies the equation.
Coefficient: A coefficient is a numerical factor that multiplies a variable in an algebraic expression. It represents the scale or magnitude of the variable, indicating how much of that variable is present in the expression.
Constant: A constant is a quantity in an algebraic expression or equation that has a fixed, unchanging value. It is a value that does not vary or change throughout the given context or problem.
Constant Term: The constant term in an algebraic expression or equation is the numerical value that does not have a variable associated with it. It is the term that remains constant regardless of the values assigned to the variables in the expression.
Distributive Property: The distributive property is a fundamental algebraic rule that states the product of a number and a sum is equal to the sum of the individual products. It allows for the simplification of expressions by distributing a factor across multiple terms within a parenthesis or other grouping symbol.
Equal Sign: The equal sign (=) is a mathematical symbol used to indicate that two expressions or values are equivalent or have the same value. It is a fundamental concept in algebra and is crucial for understanding and solving equations.
Equation: An equation is a mathematical statement that expresses the equality between two expressions, typically involving variables and constants. Equations are fundamental in algebra and are used to represent and solve various problems by finding the unknown values.
Identity: In mathematics, the term 'identity' refers to an equation or expression that is true for all values of the variables involved. It represents a fundamental relationship that holds regardless of the specific values assigned to the variables.
Inverse Operations: Inverse operations are mathematical operations that undo or reverse the effects of another operation. They are used to solve equations, simplify expressions, and perform calculations in various mathematical contexts.
Isolation Method: The isolation method is a technique used to solve linear equations by systematically isolating the variable on one side of the equation. This method involves performing inverse operations to isolate the variable and find its value, ensuring that the equation remains balanced on both sides.
Like Terms: Like terms are algebraic expressions that have the same variable(s) raised to the same power. They can be combined by adding or subtracting their coefficients, allowing for the simplification of algebraic expressions.
Linear Equation: A linear equation is a mathematical equation in which the variables are raised only to the first power and are connected by addition, subtraction, or equality. These equations represent a straight line when graphed on a coordinate plane.
Multi-Step Equation: A multi-step equation is a mathematical equation that requires more than one operation to solve for the unknown variable. These equations involve a sequence of steps, such as combining like terms, using the distributive property, or applying inverse operations, to isolate the variable and find its value.
Solution Set: The solution set of an equation is the set of all values of the variable(s) that make the equation true. It represents the complete set of solutions that satisfy the given equation.
Transposition: Transposition is the mathematical process of rearranging the terms in an equation to isolate a specific variable or expression on one side of the equation. It is a crucial technique used to solve equations with variables and constants on both sides.
Variable: A variable is a symbol, typically a letter, that represents an unknown or changeable quantity in an algebraic expression or equation. It is a fundamental concept in algebra that allows for the generalization of mathematical relationships and the solution of problems involving unknown values.
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