Mathematics Grade 7 15 min

Evaluate radical expressions

Evaluate radical expressions

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Introduction & Learning Objectives

Learning Objectives Define a radical expression and identify its components. Identify perfect squares up to 144. Evaluate the square root of perfect squares. Understand the inverse relationship between squaring a number and taking its square root. Evaluate simple expressions containing square roots of perfect squares. Apply the concept of square roots to solve basic geometric problems. Have you ever wondered how to find the side length of a square if you only know its area? 🤔 This lesson will unlock the secret to 'undoing' a square! In this lesson, you'll learn about radical expressions, specifically focusing on square roots. We'll discover what they are, how to evaluate them for perfect squares, and why they're important for solving real-world pro...
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Key Concepts & Vocabulary

TermDefinitionExample Radical ExpressionAn expression that contains a radical symbol (√), which indicates a root of a number.√25 is a radical expression. Radical SymbolThe mathematical symbol (√) used to denote a root, most commonly the square root.In √49, the '√' is the radical symbol. RadicandThe number or expression inside the radical symbol.In √81, the number 81 is the radicand. Square RootA number that, when multiplied by itself, gives the original number. Every positive number has two square roots (one positive, one negative), but we usually focus on the positive one (principal square root) in basic evaluation.The square root of 9 is 3, because 3 × 3 = 9. We write this as √9 = 3. Perfect SquareA number that is the result of squaring an integer (multiplying an integer by it...
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Core Formulas

Definition of Square Root If $a^2 = b$, then $a$ is a square root of $b$. The principal (positive) square root is denoted by $\sqrt{b}$. This rule tells us that finding the square root is the opposite of squaring a number. For example, since $5^2 = 25$, then $\sqrt{25} = 5$. Evaluating Perfect Squares To evaluate $\sqrt{n}$ where $n$ is a perfect square, find the positive number $x$ such that $x \times x = n$. This is the core process for evaluating square roots of perfect squares. You're looking for the base number that was squared to get the radicand. For instance, to evaluate $\sqrt{64}$, you ask 'What number multiplied by itself equals 64?' The answer is 8.

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Sample Practice Questions

Challenging
What is the value of √(80 + √1)?
A.9
B.√81
C.10
D.8
Challenging
If √x = 12, what is the value of x?
A.6
B.24
C.√12
D.144
Challenging
Evaluate the expression: (√144 + √36) / √9
A.√20
B.6
C.18
D.2

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