In this Grade 9 Saxon Algebra 1 lesson, students learn to add and subtract signed real numbers — including fractions and decimals — by rewriting expressions as addition only, grouping like signs, and applying the rules for adding integers. The lesson also covers ordering and comparing rational numbers on a number line and evaluating rational expressions using inequality symbols. Real-world application problems, such as comparing investment account growth, reinforce these skills in context.
Section 1
📘 Adding and Subtracting Real Numbers
Algebra is a powerful branch of mathematics where we use letters and symbols to represent unknown numbers and relationships in order to solve problems.
Our journey begins with the essential building blocks. In this lesson, we’ll tackle adding and subtracting real numbers, a core skill for solving any algebraic equation.
Section 2
Adding And Subtracting Signed Numbers
When solving a problem containing addition and subtraction of signed numbers, begin by writing the problem as addition only. Next, group and add the terms with like signs. Then add the terms with unlike signs.
Tired of subtraction? Just turn everything into addition! Group the positive pals and negative ninjas together first. Then, add each group separately before combining them for the final answer. It’s all about teamwork and keeping things organized!
Section 3
Rules For Adding Integers
Like Signs:
Unlike Signs (Negative Wins):
Unlike Signs (Positive Wins):
Think of it like a team game! If the signs are the same, they’re on the same team—just add their strengths and keep the team sign. If they’re different, the team with the bigger number (absolute value) wins after you subtract!
Section 4
Ordering Rational Numbers
Use a number line to order the numbers. To order from least to greatest, read the numbers on the number line from left to right. Converting fractions to decimals can make it easier to see their positions.
Order from least to greatest: .
First, convert values to decimals for easy comparison: .
Reading from left to right on the number line, the final order is: .
Imagine numbers are runners in a race, and the number line is their track! To find the order, just see who's behind (left) and who's ahead (right). Turning messy fractions into clean decimals helps you see exactly where each runner is placed.
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Section 1
📘 Adding and Subtracting Real Numbers
Algebra is a powerful branch of mathematics where we use letters and symbols to represent unknown numbers and relationships in order to solve problems.
Our journey begins with the essential building blocks. In this lesson, we’ll tackle adding and subtracting real numbers, a core skill for solving any algebraic equation.
Section 2
Adding And Subtracting Signed Numbers
When solving a problem containing addition and subtraction of signed numbers, begin by writing the problem as addition only. Next, group and add the terms with like signs. Then add the terms with unlike signs.
Tired of subtraction? Just turn everything into addition! Group the positive pals and negative ninjas together first. Then, add each group separately before combining them for the final answer. It’s all about teamwork and keeping things organized!
Section 3
Rules For Adding Integers
Like Signs:
Unlike Signs (Negative Wins):
Unlike Signs (Positive Wins):
Think of it like a team game! If the signs are the same, they’re on the same team—just add their strengths and keep the team sign. If they’re different, the team with the bigger number (absolute value) wins after you subtract!
Section 4
Ordering Rational Numbers
Use a number line to order the numbers. To order from least to greatest, read the numbers on the number line from left to right. Converting fractions to decimals can make it easier to see their positions.
Order from least to greatest: .
First, convert values to decimals for easy comparison: .
Reading from left to right on the number line, the final order is: .
Imagine numbers are runners in a race, and the number line is their track! To find the order, just see who's behind (left) and who's ahead (right). Turning messy fractions into clean decimals helps you see exactly where each runner is placed.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter