1. 3-9 Finding Square Roots Warm Up
Pre-Algebra
3-9
Finding Square Roots
Hmwk & calculator outt
Warm Up
Find the two square roots of each number.
Evaluate each expression.
±12
±16 20
119

2. Finding Square Roots
Learn to estimate square roots to a given number of decimal places and solve problems using square roots.

3. Each square root is between two integers. Name the integers.
Think: What are perfect squares close to 55? A. 55
72 = 49
82 = 64
55 is between 7 and 8.

4. Each square root is between two integers. Name the integers.
Think: What are perfect squares close to 90? B. – 90
–92 = 81
–102 = 100 90 –
is between –9 and –10.

5. Each square root is between two integers. Name the integers.
Think: What are perfect squares close to 80? A. 80
82 = 64
92 = 81
is between 8 and 9. 80

6. Each square root is between two integers. Name the integers.
Think: What are perfect squares close to 45? B. – 45
–62 = 36
–72 = 49 45 –
is between –6 and –7.

7. Use a calculator to find 500. Round to the nearest tenth.
Additional Examples 3: Using a Calculator to Estimate the Value of a Square Root
Use a calculator to find Round to the nearest tenth.
Using a calculator, ≈ ….
Rounded, is 22.4.

8. Use a calculator to find 200. Round to the nearest tenth.
Try This: Example 3
Use a calculator to find Round to the nearest tenth.
Using a calculator, ≈ ….
Rounded, is 14.1.

9. You want to sew a fringe on a square tablecloth with an area of 500 square inches. Calculate the length of each side of the tablecloth and the length of fringe you will need to the nearest tenth of an inch.
Understand the Problem
First find the length of a side. Then you can use the length of a side to find the perimeter, the length of fringe around the tablecloth.

10. Try This: Example 2 Continued
Look Back
The length 63.2 feet divided by 4 is 15.8 feet. A 15.8 foot square has an area of square feet, which is close to 250, so the answers are reasonable.

11. Lesson Quiz
Each square root is between two integers. Name the two integers.
– 456
5 and 6
–22 and –21
Use a calculator to find each value. Round to the nearest tenth.
9.4
35.0
5. A square field has an area of 2000 square feet. To the nearest foot, how much fencing would be needed to enclose the field?
179 ft