guided practice - ABS Community Portal

ANOTHER WAY
For alternative methods
for solving the problem
in Example 5, turn
to page 272 for the
Problem Solving
Workshop.
E XAMPLE 5 Model a dropped object with a quadratic function
SCIENCE COMPETITION For a science competition,
students must design a container that prevents an egg
from breaking when dropped from a height of 50 feet.
How long does the container take to hit the ground?
Solution
h 5216t 2 1 h0 Write height function.
0 5216t 2 1 50 Substitute 0 for h and 50 for h 0 .
250 5216t 2
50
} 16 5 t 2
Subtract 50 from each side.
Divide each side by 216.
6Î }
50
} 16 5 t Take square roots of each side.
61.8 ø t Use a calculator.
c Reject the negative solution, 21.8, because time must be positive.
The container will fall for about 1.8 seconds before it hits the ground.
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✓ GUIDED PRACTICE for Example 5
4.5 EXERCISES
EXAMPLES
1 and 2
on pp. 266–267
for Exs. 3–20
SKILL PRACTICE
20. WHAT IF? In Example 5, suppose the egg container is dropped from a height
of 30 feet. How long does the container take to hit the ground?
1. VOCABULARY In the expression Ï }
72 , what is 72 called?
2. ★ WRITING
Explain what it means to “rationalize the denominator”
of a quotient containing square roots.
SIMPLIFYING RADICAL EXPRESSIONS Simplify the expression.
3. Ï }
28 4. Ï }
192 5. Ï }
150 6. Ï }
3 p Ï }
27
7. 4Ï }
6 p Ï }
6 8. 5Ï }
24 p 3Ï }
10 9. Î }
5
}
16
11.
15.
8
} Ï }
3
2
}
1 2 Ï }
3
12.
16.
7
} Ï }
12
1
}
5 1 Ï }
6
HOMEWORK
KEY
13. Î }
18
}
11
17.
Ï }
2
} 4 1 Ï }
5
After a successful egg drop
5 WORKED-OUT SOLUTIONS
on p. WS1 for Exs. 17, 27, and 41
5 TAKS PRACTICE AND REASONING
Exs. 19, 34, 35, 36, 40, 41, 44, and 45
10. Î }
35
}
36
14. Î }
13
}
28
4.5 Solve Quadratic Equations by Finding Square Roots 269
18.
3 1 Ï} 7
}
2 2 Ï }
10