1. EXAMPLE 4
Using a Square Root Equation
Amusement Parks
On an amusement park ride, riders stand against a circular wall that spins. At a certain speed, the floor drops out and the force of the rotation keeps the riders pinned to the wall.
The model s = gives the speed needed to keep riders pinned to the wall. In the model, s is the speed in meters per second and r is the radius of the ride in meters. Find the speed necessary to keep riders pinned to the wall of a ride that has a radius of 2.61 meters. r

2. EXAMPLE 3
Using a Calculator
Evaluate the square root. Round to the nearest tenth, if necessary. a.
56.25 – b. 8 c.
1256 –
SOLUTION
Keystrokes
Answer
Display a.
–7.5 b.
2.8 c.
–35.4

3. Using a Square Root Equation
EXAMPLE 4
Using a Square Root Equation
SOLUTION r s =
4.95
Write equation for speed of the ride. =
4.95
2.61
Substitute 2.61 for r.
4.95 (1.62)
Approximate the square root using a calculator. =
8.019
Multiply.
The speed should be about 8 meters per second.
ANSWER

4. Solving Equations Using Square Roots
EXAMPLE 5
Solving Equations Using Square Roots 2 = a. x 64 2 = x 64
Original equation = x + – 64
Definition of square root = x + – 8
Evaluate square roots.
ANSWER
The solutions are 8 and –8.

5. Solving Equations Using Square Roots
EXAMPLE 5
Solving Equations Using Square Roots b. = 2 z 14 + 20 = 2 z 14 + 20
Original equation = 2 z + 14 –
20 – 14
Subtract 14 from each side. = 6 2 z
Simplify. 6 z + – =
Definition of square root
z ≈ + –
2.4
Approximate square roots.
ANSWER
The solutions are about 2.4 and –2.4.

6. GUIDED PRACTICE
for Examples 3, 4 and 5
Use a calculator to evaluate. Round to the nearest tenth. 9.
236
ANSWER
15.4

7. GUIDED PRACTICE
for Examples 3, 4 and 5
Use a calculator to evaluate. Round to the nearest tenth.
10. 11
ANSWER
3.3

8. GUIDED PRACTICE
for Examples 3, 4 and 5
Use a calculator to evaluate. Round to the nearest tenth.
11.
20.96 –
ANSWER
–4.6

9. GUIDED PRACTICE
for Examples 3, 4 and 5
Use a calculator to evaluate. Round to the nearest tenth.
12.
3590 –
ANSWER
–59.9

10. GUIDED PRACTICE
for Examples 3, 4 and 5
13. t = + _ t = 6
ANSWER

11. GUIDED PRACTICE
for Examples 3, 4 and 5
14. k = 2
121 = x + – 11
ANSWER

12. GUIDED PRACTICE
for Examples 3, 4 and 5
15. = 2 y 15 – 10
ANSWER + – y 5 =

13. GUIDED PRACTICE
for Examples 3, 4 and 5
16. = 2 x 7 + 16
ANSWER x + – 3 =