Real Numbers And The Pythagorean Theorem Worksheet - Chapter 7 Page 25

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Approximating a Square Root
2 2
EXAMPLE
Estimate
71 to the nearest (a) integer and (b) tenth.
a. Make a table of numbers whose squares are close to 71.
Number
7
8
9
10
Square of Number
49
64
81
100
The table shows that 71 is between the perfect squares 64 and 81.
Because 71 is closer to 64 than to 81,
71 is closer to 8 than to 9.
49
64
71
81
100
7
8
9
10
71 ≈ 8.
So,
b. Make a table of numbers between 8 and 9 whose squares are
close to 71.
Number
8.3
8.4
8.5
8.6
Square of Number
68.89
70.56
72.25
73.96
Study Tip
Because 71 is closer to 70.56 than to 72.25,
71 is closer to 8.4
than to 8.5.
You can continue the
process shown in
Example 2 to
68.89
70.56
71
72.25
73.96
approximate square
roots using more
8.3
8.4
8.5
8.6
decimal places.
71 ≈ 8.4.
So,
Estimate the square root to the nearest (a) integer and (b) tenth.
Exercises 20–25
5. −
6. −
4.
8
13
24
7.
110
3 3
Comparing Real Numbers
EXAMPLE
2
Which is greater,
5 or 2
?
3
Estimate
5 to the nearest integer. Then graph the numbers on
a number line.
2
2
2.6
5
2
3
4
2
9
3
2
2
2
is to the right of
5 . So, 2
is greater.
3
3
Section 7.4
Approximating Square Roots
311

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