Lesson 9-1 Pages 436-440
Squares and
Square Roots
Read Pages 436-438
PA Lesson Check 7-Ch7
What you will learn!
1. How to find squares and
square roots.
2. How to estimate square
roots.
Perfect Square
Square root
Radical 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.
What you really need to know!
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.
Square
Square Root
Example 1:
Find the square root:
64
Since
2
8
= 64,
64  8
Example 1b:
Find the square root:
 121
Since
2
11
= 121,
 121  11
Example 1c:
Find the square root:
 4
Since
2
2
= 4 and
2
(-2)
= 4,
 4  2 and  2
Example 2:
Use a calculator to fine the
square root to the nearest tenth.
23
23  4.79583152331271
4.8
Example 2b:
Use a calculator to fine the
square root to the nearest tenth.
 46
 46  6.78232998312527
-6.8
Example 3:
Estimate the square root to the
nearest whole number.
22
The perfect squares are:
1, 4, 9, 16, 25, 36, 49, 64, 81,
100, 121, 144, 169, ...
22 is between 16 and 25.
16  4 and 25  5
22
The perfect squares are:
1, 4, 9, 16, 25, 36, 49, 64, 81,
100, 121, 144, 169, ...
22 is closer to 25. So 5 is
the best estimate for the
square root of 22.
22  5
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.
 319
The perfect squares are:
..., 169, 196, 225, 256, 289,
324, 361, ...
319 is between 289 and 324.
289  17 and 324  18
 319
The perfect squares are:
..., 169, 196, 225, 256, 289,
324, 361, ...
319 is closer to 325. So 18
is the best estimate for the
square root of 319.
 319  18
The perfect squares are:
..., 169, 196, 225, 256, 289,
324, 361, ...
Example 4:
To estimate how far you can see
from a point above the horizon,
you can use the formula:
D  1.22  A
where D is the distance in miles
and A is the altitude, or height, in
feet.
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.
D  1.22  A
D  1.22  A
D  1.22  520
D  1.22  22.8035085019828
D  27.820280372419
D  27.8mi
Page 438
Guided Practice
#’s 4-11
Read:
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