#  >> K-12 >> K-12 Basics

How to Use an Associative Law to Find an Equivalent Expression

In mathematics, the associative law states that the sum or product of three or more numbers will always be the same regardless of the grouping. For example, the additive associative states that (5 + 6) + 3 and 5 + (6 + 3) will both equal 14, and the multiplicative associative law states that (3 x 4) x 8 and 3 x (4 x 8) will both equal 96. Using the associative law, large expressions can be simplified by evaluating smaller values first, which will create an equivalent expression that has the same mathematical value as the original expression.

Instructions

  1. Additive Associative Law

    • 1

      Examine the expression (7 + 8) + 11. Following the order of operations, this expression simplifies to (15) + 11 = 26.

    • 2

      Reorder the grouping symbols to enclose the last two terms instead of the first two: 7 + (8 + 11). Do not reorder the terms; that is the commutative law of addition.

    • 3

      Solve for the new grouped terms and simplify the expression to check for equality: 7 + (19) = 26. Therefore, (7 + 8) + 11 and 7 + (8 + 11) are equivalent expressions and have the same numerical value.

    • 4

      Examine the expression (5 + 3x) + 6. Once the parentheses are removed and the like terms are combined, the sum of this expression is 11 + 3x.

    • 5

      Regroup the terms within the expression: 5 + (3x + 6).

    • 6

      Simplify the second expression to check for equality. Remove the parentheses and combine like terms: 5 + 3x + 6 = 11 + 3x. Therefore, the equivalent expressions are (5 + 3x) + 6 = 5 + (3x + 6).

    Multiplicative Associative Law

    • 7

      Examine the expression (-9 x -4) x -2. Following the order of operations to simplify the expression, the product of the terms is (36) x -2 = -72.

    • 8

      Regroup the terms within the expression: -9 x (-4 x -2).

    • 9

      Follow the order of operations to simplify the expression and check for equality: -9 x (8) = -72.

    • 10

      Examine the expression (5n x 4n) x 6. Simplify the expression by removing the parentheses and combining like terms. In this case, 5n x 4n x 6 = 20n^2 x 6.

    • 11

      Regroup the terms to create an equivalent expression: 5n x (4n x 6).

    • 12

      Simplify the expression for equality: 5n x 4n x 6 = 20n^2 x 6.

Learnify Hub © www.0685.com All Rights Reserved