Let’s solve each part of the worksheet step by step.
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##
Graphing Absolute Value Functions
The general form is:
f(x) = a|x - h| + k
- Vertex: (h, k)
- If
a > 0, opens upward; if
a < 0, opens downward.
- Domain: always all real numbers →
(-∞, ∞)
- Range: depends on vertex and direction:
- Upward: [k, ∞)
- Downward: (-∞, k]
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1. f(x) = |x| + 2
This is
f(x) = 1|x - 0| + 2
✔ Vertex: (0, 2)
✔ Domain: All real numbers →
(-∞, ∞)
✔ Range: Since it opens upward, minimum y-value is 2 →
[2, ∞)
Graphing tips:
- Plot vertex at (0,2)
- Use slope ±1 from vertex:
- Right: (1,3), (2,4)
- Left: (-1,3), (-2,4)
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2. f(x) = -|x - 4|
This is
f(x) = -1|x - 4| + 0
✔ Vertex: (4, 0)
✔ Domain:
(-∞, ∞)
✔ Range: Opens downward → maximum y-value is 0 →
(-∞, 0]
Graphing tips:
- Plot vertex at (4,0)
- Slope: ±(-1) → from vertex, go down 1 for every 1 right or left:
- Right: (5,-1), (6,-2)
- Left: (3,-1), (2,-2)
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3. f(x) = -3|x| + 5
This is
f(x) = -3|x - 0| + 5
✔ Vertex: (0, 5)
✔ Domain:
(-∞, ∞)
✔ Range: Opens downward → max y = 5 →
(-∞, 5]
Graphing tips:
- Vertex at (0,5)
- Slope: ±(-3) → steeper V-shape
- Right: (1,2), (2,-1)
- Left: (-1,2), (-2,-1)
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4. f(x) = |x + 1| - 1
This is
f(x) = 1|x - (-1)| - 1
✔ Vertex: (-1, -1)
✔ Domain:
(-∞, ∞)
✔ Range: Opens upward → min y = -1 →
[-1, ∞)
Graphing tips:
- Vertex at (-1, -1)
- Slope ±1:
- Right: (0,0), (1,1)
- Left: (-2,0), (-3,1)
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##
Charles’ Pricing Function: f(x) = 5|x - 8| + 20
Here,
x = number of hours,
f(x) = hourly rate in dollars
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5. How much does Charles charge per hour if a customer hires him for 3 hours?
Plug
x = 3 into the function:
f(3) = 5|3 - 8| + 20
= 5|-5| + 20
= 5(5) + 20
= 25 + 20
=
$45 per hour
✔ Answer: $45 per hour
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6. Find the lowest hourly rate that Charles charges. Show your work.
We are looking for the
minimum value of f(x) = 5|x - 8| + 20
Since absolute value is always ≥ 0, the smallest |x - 8| can be is
0, which occurs when
x = 8.
So:
f(8) = 5|8 - 8| + 20
= 5(0) + 20
=
20
✔ Lowest hourly rate: $20 per hour
*(This happens when the customer hires him for exactly 8 hours.)*
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##
✔ Final Answers Summary:
Graphing Problems:
1.
f(x) = |x| + 2
- Vertex: (0, 2)
- Domain: (-∞, ∞)
- Range: [2, ∞)
2.
f(x) = -|x - 4|
- Vertex: (4, 0)
- Domain: (-∞, ∞)
- Range: (-∞, 0]
3.
f(x) = -3|x| + 5
- Vertex: (0, 5)
- Domain: (-∞, ∞)
- Range: (-∞, 5]
4.
f(x) = |x + 1| - 1
- Vertex: (-1, -1)
- Domain: (-∞, ∞)
- Range: [-1, ∞)
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Charles’ Problem:
5. For 3 hours →
$45 per hour
6. Lowest hourly rate →
$20 per hour (when x = 8)
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You can now graph each function using the vertices and slopes as described above. Let me know if you want hand-drawn sketches or digital plots!
Parent Tip: Review the logic above to help your child master the concept of absolute value graphs worksheet.