Solve OneStep Addition and Subtraction Equations Section 4

Solve One-Step Addition and Subtraction Equations Section 4. 3 Objective: To solve addition and subtraction equations

WHAT IS AN EQUATION? “Equation” sounds like a big complicated word, but it’s not. An equation is basically just like a balance scale - it shows two quantities are equal.

WHAT IS AN EQUATION? When you do something to one side of a balance, you must do the same to the other side to keep it balanced.

Solving for a mysterious number sounds hard… but it’s not! “X” likes to be alone. He doesn’t have many friends, but he is a master of disguise – he can be anything! So, when you see “X” in an equation, you need to get him alone, then he will reveal his true identity to you!

Vocabulary Term Definition 1. Equivalent equation 2. Addition Property of Equality 3. Subtraction property of Equality 4. Solution 5. Equation

Vocabulary • An _____ is a sentence stating that two quantities are equal. • The value of a variable that makes an equation true is called the ____ of the equation.

Notes • Remember, equations must always remain ________. • If you subtract the same number from each side of an equation, the two sides remain _______. • If you add the same number to each side of an equation, the two sides also remain equal.

Real-World Link • Robyn had some video games, and then she bought 4 more games. She now has 10 games. This scenario can be described using the equation x + 4 = 10. • 1. What does x represent in the equation? • ____________________ • 2. Write two different equations that are equivalent to x + 4 = 10 • _______________________________________

Subtraction Property of Equality Words The Subtraction Property of Equality states that the two sides of an equation remain equal when you subtract the same number from each side. Symbols If a = b, then a – c = b - c

CHECK IT OUT! x + 7 = 24 See how 24 is on one side of the equal sign? X and 7 are on the other side. Remember how ‘x’ likes to be alone? Let’s get it that way! When you think solving equations, think opposite operations. What is the opposite of addition? That’s right, subtraction! So you see (x + 7) up there, this means you use subtraction. x + 7 = 24 When you do something to one side of an equation, you must do the same thing to the other side. -7 -7 x = 17 Now ‘x’ is alone and you know he was actually 17!

Examples • 1. y + 6 = 9 • 2. x + 3 = 1 • 3. -3 = a + 4

Word Problem • The highest recorded temperature in Warsaw, Missouri, is 118 degrees F. This is 158 degrees greater than the lowest recorded temperature. Write and solve an equation to find the lowest recorded temperature.

Addition Property of Equality Words The Addition Property of Equality states that the two sides of an equation remain equal when you add the same number from each side. Symbols If a = b, then a + c = b + c

Word Problem • The average lifespan of a tiger is 17 years. This is 3 years less than the average lifespan of a lion. Write and solve an equation to find the average lifespan of a lion.

Try it Out • 10. 2. 9 + z = -1. 2 • 11. -1 and 3/8 = x – ½ • 12. -31 = r - 36

H. O. T. Problem • Is the following statement always, sometimes, or never true? Explain your reasoning. – If a + x = 100, then x is less than 100

Essential Question • What are two methods for solving a real-world problem that can be represented by an equation? • _____________________________________ ___________________