HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Section 8.1 Solving Linear Equations: x  b  c and ax  c

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Objectives o Define the term “linear equation.” o Solve equations of the form x  b  c. o Solve equations of the form ax  c.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Linear Equations Linear Equation in x If a, b, and c are constants and then a linear equation in x is an equation that can be written in the form Note: A linear equation in x is also called a first-degree equation in x because the variable x can be written with the exponent 1. That is,

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form x + b = c Addition Principle of Equality If the same algebraic expression is added to both sides of an equation, the new equation has the same solutions as the original equation. Symbolically, if A, B, and C are algebraic expressions, then the equations A = B and A + C = B + C have the same solutions.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form x + b = c Procedure for Solving Linear Equations that Simplify to the Form x  b  c 1.Combine any like terms on each side of the equation. 2.Use the addition principle of equality and add the opposite of the constant b to both sides. The objective is to isolate the variable on one side of the equation (either the left side or the right side) with a coefficient of +1.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form x + b = c Procedure for Solving Linear Equations that Simplify to the Form x  b  c (cont.) 3.Check your answer by substituting it for the variable in the original equation.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 1: Solving x  b  c Solve the equation x  3  7. Solution Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 2: Solving x  b  c Solve the equation  11  y  5. Solution Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 3: Solving x  b  c Solve the equation Solution Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 4: Solving x  b  c Solve the equation Solution

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 4: Solving x  b  c (cont.) Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 5: Simplifying and Solving Equations Simplify and solve the equation Solution

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 5: Simplifying and Solving Equations (cont.) Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Completion Example 6: Simplifying and Solving Equations Supply the reasons for each step in solving the equation. Solution

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form ax = c Multiplication (or Division) Principle of Equality If both sides of an equation are multiplied by (or divided by) the same nonzero constant, the new equation has the same solutions as the original equation. Symbolically, if A and B are algebraic expressions and C is any nonzero constant, then the equations A = B and AC = BC where

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form ax = c Multiplication (or Division) Principle of Equality (cont.) and where have the same solutions. We say that the equations are equivalent.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form ax = c Procedure for Solving Linear Equations that Simplify to the Form ax  c 1.Combine any like terms on each side of the equation. 2.Use the multiplication (or division) principle of equality and multiply both sides of the equation by the reciprocal of the coefficient of the variable. (Note: This is the same as dividing both sides of the equation by the coefficient.) Thus the coefficient of the variable will become +1.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Solving Equations of the Form ax = c (cont.) Procedure for Solving Linear Equations that Simplify to the Form ax  c (cont.) 3.Check your answer by substituting it for the variable in the original equation.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 7: Solving ax = c Solve the equation 5x = 20. Solution

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 7: Solving ax = c (cont.) Check Multiplying by the reciprocal of the coefficient is the same as dividing by the coefficient itself. So, we can multiply both sides by as we did, or we can divide both sides by 5.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 7: Solving ax = c (cont.) In either case, the coefficient of x becomes +1.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 8: Solving ax = c Solve the following equation. 1.1x + 0.2x = 12.2 − 3.1 Solution When decimal coefficients or constants are involved, you might want to use a calculator to perform some of the arithmetic.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 8: Solving ax = c (cont.) Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 9: Solving ax = c Solve the following equation. −x = 4 Solution

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 9: Solving ax = c (cont.) Check

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Completion Example 10: Solving ax = c Supply the reasons for each step in solving the following equation.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Completion Example 10: Solving ax = c (cont.) Solution

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 11: Application Mark had a coupon for $50 off the Blu-Ray player he just purchased. With the coupon, the price was $ Solve the equation y − 50 = to determine the original price of the Blu-Ray player.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Example 11: Application (cont.) Solution y − 50 = y − = Use the addition principle by adding 50 to both sides. y = Simplify. The original price of the Blu-Ray player was $

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Practice Problems Solve the following equations. 1.  16 = x  52. 6y  1.5 = x =  z + 2.4z =  x =  x = x  4x =  2.79.

HAWKES LEARNING SYSTEMS Students Matter. Success Counts. Copyright © 2013 by Hawkes Learning Systems/Quant Systems, Inc. All rights reserved. Practice Problem Answers 1. x =  212. y = x =  5 4. y = 555. z = 26. x = x =  4.39.