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Lesson 9-1 Pages 436-440 Squares and Square Roots PA Lesson Check 7-Ch7 Read Pages 436-438

# Lesson 9-1 Pages 436-440 Squares and Square Roots PA Lesson Check 7-Ch7 Read Pages 436-438

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Lesson 9-1 Pages 436-440

Squares and Square Roots

PA Lesson Check 7-Ch7

What you will learn!1. How to find squares and square roots.

2. How to estimate square roots.

Perfect SquarePerfect Square

What you really need to know!

A perfect square is the square of a whole number.

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.The square root of a negative number such as –25, is not real because the square of a number is never negative.

What you really need to know!

Square Square Root

Example 1:

Find the square root:

64Since 82 = 64,

864

Example 1b:

Find the square root:

121Since 112 = 121,

11121

Example 1c:

Find the square root:

4Since 22 = 4 and (-2)2 = 4,

2 and 24

Example 2:

Use a calculator to fine the square root to the nearest tenth.

233312714.7958315223

4.8

Example 2b:

Use a calculator to fine the square root to the nearest tenth.

463125276.7823299846

-6.8

Example 3:

Estimate the square root to the nearest whole number.

22The perfect squares are:

1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, ...

22 is between 16 and 25.

The perfect squares are:

1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, ...

525 and 416

22

22 is closer to 25. So 5 is the best estimate for the square root of 22.

522 The perfect squares are:

1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, ...

Example 3b:

Estimate the square root to the nearest whole number.

319The perfect squares are:

..., 169, 196, 225, 256, 289, 324, 361, ...

319 is between 289 and 324.

81324 and 17289

The perfect squares are:

..., 169, 196, 225, 256, 289, 324, 361, ...

319

319 is closer to 325. So 18 is the best estimate for the square root of 319.

18319 The perfect squares are:

..., 169, 196, 225, 256, 289, 324, 361, ...

Example 4:

where D is the distance in miles and A is the altitude, or height, in feet.

To estimate how far you can see from a point above the horizon, you can use the formula:

Example 4:

The observations deck at the Seattle Space Needle is 520 feet above the ground. On a clear day, about how far could a tourist see? Round to the nearest tenth.

52022.1 D01982822.803508522.1 D

7241927.8202803D27.8miD

Page 438

Guided Practice

#’s 4-11

Pages 436-438 with someone at home and

study examples!

Homework: Pages 439-440

#’s 12-56 even, 71-80

Lesson Check 9-1

Homework: Pages 439-440

#’s 12-56 even

#’s 59, 60 and 71-74

Page

745

Lesson 9-1

Lesson Check 9-1