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Lesson 9-1 Pages 436-440
Squares and Square Roots
PA Lesson Check 7-Ch7
Read Pages 436-438
What you will learn!1. How to find squares and square roots.
2. How to estimate square roots.
Perfect SquarePerfect Square
Square rootSquare rootRadical signRadical sign
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:
AD 22.1
Example 4:
AD 22.1
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.
AD 22.1
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!
Read:
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