Page 59 - Math Course 2 (Book 1)

Squares and Square Roots

Mo. 2

Lesson 3 Key Concept

KEY CONCEPTS: Square Root
1. Find squares and square roots.
2. Estimate square roots. Words A square root of a number is one of its
two equal factors.

2
Symbols If x = y, then x is a square root of y.
MO. 2 - L3a
Example Since 5 • 5 = 5 = 25, 5 is a square root
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Finding Squares and of 25.
Square Roots Since (–5) • (–5) or (–5) = 25, is –5 is
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a square root of 25.
Vocabulary A-Z

Let us learn some vocabulary
Let’s Begin

Perfect square
Find Square Roots
is an integer that is the square of an integer; in other
words, it is the product of some integer with itself. It
is sometimes called a square number.
Examples
2
2
2
1 = 1 5 = 25 9 = 81
2
2 = 4 6 = 36 10 = 100 Find 64
2
2
3 = 9 7 = 49 11 = 121
2
2
2
4 = 16 8 = 64 12 = 144 64 indicates the positive square root of 64.
2
2
2
2
64
Since 8 = 64, = 8.
Square root
Answer 8
A square root of a number is one of two equal
factors of the number. Every positive number has a
positive square root and a negative square root.
Find – 121
Since 5 • 5 or 5 = 25, 5 is a square root
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of 25. – 121 indicates the negative square root of 121.
Since 11 = 121, = –11.
– 121
2
2
Since (–5) • (–5) or (–5) = 25, –5 is a
square root of 25.
Answer –11
Radical sign
A radical sign is used to indicate a positive square
root. Find + 256
36
what is ? + 256 indicates the both square roots of 256.
1. Def nition 2. Guess and Check
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– 256
256
1 = 1 Since 16 = 256, = 16 and = –16.
2
a² = b 2 = 4
2
36 3 = 9 36 = 6
2
indicates the b = a 4 = 16 Answer +16 and –16
2
positive square 5 = 25
2
root of 36. 6 = 36
2
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