Section 2.2 The Addition Property of Equality 103 This property tells us that if two expressions are equal, we can • add the same number to both expressions and the expressions will remain equal. • subtract the same number from both expressions and the expressions will remain equal. Example 2 illustrates the most basic use of the addition property of equality. We will use this property to solve for the variable in one step. Using the Addition Property of Equality to Solve an Equation Step 1: Determine the operation that will isolate the variable on one side of the equation. Perform this operation on each side of the equation. Remember the inverse property for addition: a + (-a) = -a + a = a - a = 0. Step 2: Simplify each side of the equation, as necessary. The result should be of the form x = some number or some number = x Step 3: Check the solution by substituting the value into the original equation. Step 4: Write the solution in set notation. Solve each equation using the addition property of equality. Check each answer. 2a. x + 12 = 10 2b. y - 7 = -13 2c. b + 1 2 =- 3 2 2d. 1.8 = 2.1 + r Solutions 2a. x + 12 = 10 x + 12 - 12 = 10 - 12 Subtract 12 from each side. x=-2 Simplify. Check: x + 12 = 10 Original equation -2 + 12 = 10 Replace x with -2. 10 = 10 Simplify. Since x = -2 makes the equation true, the solution set is {-2}. 2b. y - 7 = -13 y - 7 + 7 = -13 + 7 Add 7 to each side. y = -6 Simplify. Check: y - 7=-13 Original equation -6 - 7=-13 Replace y with -6. -13=-13 Simplify. Since y = -6 makes the equation true, the solution set is {-6}. 2c. b + 1 2 =- 3 2 b + 1 2 - 1 2 =- 3 2 - 1 2 Subtract 1 2 from each side of the equation. b=- 4 2 Simplify each side. b=-2 Simplify the fraction.
hendricks_beginning_algebra_1e_ch1_3
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