Lesson Notes By Weeks and Term v4 - JHS 1

Lesson Video

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Performance objectives

• Define an algebraic expression and its parts.
• Add algebraic expressions with like terms.
• Subtract algebraic expressions with like terms.
• Combine addition and subtraction operations.
• Solve real-life problems using these skills.

Lesson summary

This lesson introduces the fundamental skills of adding and subtracting algebraic expressions. Algebra is like a special language for solving problems. Imagine trying to calculate the total cost of 5 exercise books and 3 pens without knowing their prices yet. We can use letters (like 'x' for the price of a book and 'y' for the price of a pen) to represent these unknown values. Learning to combine these expressions helps us solve real-life problems, from managing a small provisions shop to calculating materials needed for a building project. It is a foundational skill for all higher mathematics.

Lesson notes

A. What are Algebraic Expressions? An algebraic expression is a mathematical phrase that can contain ordinary numbers, variables (like x or y), and operators (like add, subtract, multiply, divide).

Variable: A letter that represents an unknown number. E.g., `a`, `b`, `p`, `q`. Coefficient: The number that is multiplied by a variable. In `5x`, the coefficient is `5`. Constant: A term without a variable. In `5x + 7`, the constant is `7`. B. The Most Important Idea: Like Terms and Unlike Terms To add or subtract algebraic expressions, we can only combine "like terms". Like Terms: These are terms that have the *exact same variable(s)* raised to the *exact same power*. The coefficients can be different. Analogy: Think of a market seller. You can add 3 yams and 4 yams to get 7 yams. You can add 5 mangoes and 2 mangoes to get 7 mangoes. Yams are 'like' yams, and mangoes are 'like' mangoes. Examples: `3x` and `8x` are like terms (same variable 'x'). `7p` and `-2p` are like terms. `5ab` and `ab` are like terms (same variables 'a' and 'b'). Note that `ab` has a coefficient of `1`. `4y²` and `9y²` are like terms (same variable 'y' to the same power of 2). Unlike Terms: These are terms with different variables or the same variable raised to different powers. Analogy: You cannot add 3 yams and 5 mangoes to get "8 yam-mangoes". You can only say you have "3 yams and 5 mangoes". Examples: `3x` and `5y` are unlike terms (different variables). `4a` and `9` are unlike terms (one has a variable, one is a constant). `2p` and `6p²` are unlike terms (same variable, but different powers). C. How to Add Algebraic Expressions

The rule is simple: Group the like terms and add their coefficients.

Reference guide

• for a building project. It is a foundational skill for all higher mathematics.
• Learning Objectives:
• By the end of this lesson, the learner will be able to:
• Identify and define like and unlike terms in an algebraic expression.
• Group like terms together to prepare an expression for simplification.
• Add two or more algebraic expressions by combining like terms.