Holt Algebra 1 11-5 Square-Root Functions 11-5 Square-Root Functions Holt Algebra 1 Warm Up Warm Up...
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Transcript of Holt Algebra 1 11-5 Square-Root Functions 11-5 Square-Root Functions Holt Algebra 1 Warm Up Warm Up...
Holt Algebra 1
11-5 Square-Root Functions11-5 Square-Root Functions
Holt Algebra 1
Warm UpWarm Up
Lesson PresentationLesson Presentation
Lesson QuizLesson Quiz
Holt Algebra 1
11-5 Square-Root Functions
Warm Up
Find each square root.
1.
3.
Solve each inequality.
5. x + 5 ≥ 0
7. 0 ≤ 3x
6 2.
4.
6. 0 ≤ 4x – 8
8. 10 – 3x ≥ 0
12
–20 undefined
x ≥ –5 x ≥ 2
x ≥ 0
Holt Algebra 1
11-5 Square-Root Functions
Warm Up Continued
Compare. Write <, >, or =.
9. 7
10. 3
<
>
Holt Algebra 1
11-5 Square-Root Functions
Identify square-root functions and their domains and ranges.
Graph square-root functions.
Objectives
Holt Algebra 1
11-5 Square-Root Functions
The function gives the speed in feet per second of an object in free fall after falling x feet. This function is different from others you have seen so far. It contains a variable under the square-root sign, .
Holt Algebra 1
11-5 Square-Root Functions
Example 1A: Evaluating Square-Root Functions
Write the speed function.
Substitute 16 for x.
Simplify.
The function gives the speed in feet per second of an object in free fall after falling x feet.
Find the speed of an object in free fall after it has fallen 16 feet.
= 8(4)
= 32After an object has fallen 16 feet, its speed is 32 ft/s.
Holt Algebra 1
11-5 Square-Root Functions
Write the speed function.Substitute 20 for x. Use a
calculator to find the square root.
Simplify.
The function gives the speed in feet per second of an object in free fall after falling x feet.
Find the speed of an object in free fall after it has fallen 20 feet. Round your answer to the nearest tenth.
= 8(4.47)
≈ 35.8
Example 1B: Evaluating Square-Root Functions
After an object has fallen 20 feet, its speed is about 35.8 ft/s.
Holt Algebra 1
11-5 Square-Root Functions
Write the speed function.
Substitute 25 for x.
Simplify.
The function gives the speed in feet per second of an object in free fall after falling x feet.
Find the speed of an object in free fall after it has fallen 25 feet.
= 8(5)
= 40After an object has fallen 25 feet, its speed is 40 ft/s.
Check It Out! Example 1a
Holt Algebra 1
11-5 Square-Root Functions
Check It Out! Example 1b
Write the speed function.
Substitute 15 for x. Use a calculator to find the square root.
Simplify.
The function gives the speed in feet per second of an object in free fall after falling x feet.Find the speed of an object in free fall after it has fallen 15 feet. Round your answer to the nearest hundredth.
= 8(3.87)
≈ 30.98After an object has fallen 15 feet, its speed is about 30.98 ft/s.
Holt Algebra 1
11-5 Square-Root Functions
Recall that the square root of a negative number is not a real number. The domain (x-values) of a square-root function is restricted to numbers that make the value under the radical sign greater than or equal to 0.
Holt Algebra 1
11-5 Square-Root Functions
Example 2A: Finding the Domain of Square-root Functions
Find the domain of the square-root function.
x– 4 ≥ 0
+ 4 + 4
x ≥ 4
The expression under the radical sign must be greater than or equal to 0.
Solve the inequality. Add 4 to both sides.
The domain is the set of all real numbers greater than or equal to 4.
Holt Algebra 1
11-5 Square-Root Functions
Find the domain of the square-root function.
x + 3 ≥ 0
–3 –3
x ≥ –3
The expression under the radical sign must be greater than or equal to 0.
Solve the inequality. Subtract 3 from both sides.
The domain is the set of all real numbers greater than or equal to –3.
Example 2B: Finding the Domain of Square-root Functions
Holt Algebra 1
11-5 Square-Root Functions
Check It Out! Example 2a
Find the domain of the square-root function.
The expression under the radical sign must be greater than or equal to 0.
Solve the inequality. Add 1 to both sides.
2x – 1 ≥ 0+1 +1
2x ≥ 1
Divide both sides by 2.
The domain is the set of all real numbers greater than or equal to .
Holt Algebra 1
11-5 Square-Root Functions
Check It Out! Example 2b
Find the domain of the square-root function.
The expression under the radical sign must be greater than or equal to 0.3x – 5 ≥ 0
+ 5 +53x ≥ 5
Solve the inequality. Add 5 to both sides.
Divide both sides by 3.
The domain is the set of all real numbers greater than or equal to .
Holt Algebra 1
11-5 Square-Root Functions
The parent function for square-root functions, is graphed at right. Notice there are no x-values to the left of 0 because the domain is x ≥ 0.
Holt Algebra 1
11-5 Square-Root Functions
If a square-root function is given in one of these forms, you can graph the parent function and translate it vertically or horizontally.
Holt Algebra 1
11-5 Square-Root Functions
Example 3A: Graphing Square-Root Functions
Graph .
Graph f(x) = and then shift the graph 3 units to the right.
Since this function is in the form f(x) = , you can graph it as a horizontal translation of the graph of f(x) =
Holt Algebra 1
11-5 Square-Root Functions
Example 3B: Graphing Square-Root Functions
Graph .
This is not a horizontal or vertical translation of .
Step 1 Find the domain of the function.
x ≥ 0 The expression under the radical sign must be greater than or equal to 0.
The domain is the set of all real numbers greater than or equal to 0.
Holt Algebra 1
11-5 Square-Root Functions
Example 3B Continued
Step 2 Choose x-values greater than or equal to 0 and generate ordered pairs.
Step 3 Plot the points. Then connect them with a smooth curve.
11.356
104
71
40
x
Graph .
Holt Algebra 1
11-5 Square-Root Functions
Check It Out! Example 3a
Graph each square root function.
Graph f(x) = and then shift the graph 2 units up.
Since this function is in the form f(x) = , you can graph it as a vertical translation of the graph of f(x) =
Holt Algebra 1
11-5 Square-Root Functions
Check It Out! Example 3b
Graph each square root function.
This is not a horizontal or vertical translation of .
Step 1 Find the domain of the function.
x ≥ 0The expression under the radical sign
must be greater than or equal to 0.
The domain is the set of all real numbers greater than or equal to 0.
Holt Algebra 1
11-5 Square-Root Functions
Check It Out! Example 3b Continued
Step 2 Choose x-values greater than or equal to 0 and generate ordered pairs.
Graph .
7.896
74
51
30
x
Step 3 Plot the points. Then connect them with a smooth curve.
Holt Algebra 1
11-5 Square-Root Functions
Lesson Quiz: Part I
1. Use the formula to find the radius of a circle
whose area is 28 in2. Use 3.14 for . Round your
answer to the nearest tenth of an inch.
Find the domain of each square-root function.
3.0 in.
x ≥ 0
x ≥ 5
2.
3.
4.