Math Problem Statement

The function T(x) = 0.15(x − 1500) + 150 represents the tax bill T of a single person whose adjusted gross income is x dollars for income between $1,500 and $64,400. Inclusive. (a) What is the domain of this linear function? (b) What is a single filer’s tax bill if the adjusted gross income is $16,000? (c) Which variable is independent and which is dependent? (d) Graph the linear function over the domain specified in part (a). (e) What is a single filer’s adjusted gross income if the tax bill is $4,350?

Solution

Let's solve each part of the problem step by step based on the function T(x)=0.15(x1500)+150T(x) = 0.15(x - 1500) + 150, which represents the tax bill TT of a single person with an adjusted gross income xx between $1,500 and $64,400 inclusive.

(a) Domain of the linear function

The domain of the function is the range of values that xx, the adjusted gross income, can take. The income range is given as between $1,500 and $64,400. Hence, the domain is:

[1500,64400][1500, 64400]

(b) Tax bill if adjusted gross income is $16,000

We need to substitute x=16000x = 16000 into the function T(x)T(x):

T(16000)=0.15(160001500)+150T(16000) = 0.15(16000 - 1500) + 150 T(16000)=0.15(14500)+150=2175+150=2325T(16000) = 0.15(14500) + 150 = 2175 + 150 = 2325

So, the tax bill would be $2,325.

(c) Which variable is independent and which is dependent?

  • The adjusted gross income xx is the independent variable.
  • The tax bill T(x)T(x) is the dependent variable since it depends on the income.

Thus, option A is the correct answer.

(d) Graph the function

We know the function T(x)=0.15(x1500)+150T(x) = 0.15(x - 1500) + 150 is linear, starting at x=1500x = 1500 and going up to x=64400x = 64400. From the options provided:

  • The function starts at a low value (when x=1500x = 1500) and increases as xx increases.
  • Since it's a linear function with a positive slope, option C is the correct graph.

(e) Adjusted gross income when the tax bill is $4,350

We need to solve for xx when T(x)=4350T(x) = 4350:

4350=0.15(x1500)+1504350 = 0.15(x - 1500) + 150 4350150=0.15(x1500)4350 - 150 = 0.15(x - 1500) 4200=0.15(x1500)4200 = 0.15(x - 1500) x1500=42000.15=28000x - 1500 = \frac{4200}{0.15} = 28000 x=28000+1500=29500x = 28000 + 1500 = 29500

So, the adjusted gross income would be $29,500.


Would you like more details or have any questions about any part of the solution? Here are 5 related questions to deepen your understanding:

  1. What does the slope of the linear function represent in this context?
  2. How would the tax bill change if the income limit was increased to $70,000?
  3. Can you calculate the tax bill for an income of $40,000?
  4. How would the function change if the tax rate (0.15) were increased to 0.20?
  5. What would be the adjusted gross income if the tax bill were $5,000?

Tip: For linear functions, the coefficient of xx (the slope) directly shows how much the dependent variable changes with each unit increase in the independent variable.

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Math Problem Analysis

Mathematical Concepts

Linear Functions
Algebra

Formulas

T(x) = 0.15(x − 1500) + 150
Domain of a linear function
Solving for the dependent variable

Theorems

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Suitable Grade Level

Grades 9-11