Lesson 20
Rational Equations (Part 1)
Problem 1
A local office supply store charges $18 to set up their business card printing machine with the design and $0.15 in materials per business card to print. Select all equations that could represent an expression for the average cost \(A(x)\) of printing a batch of \(x\) business cards.
\(A(x)=\frac{18+x}{0.15}\)
\(A(x)=\frac{18+0.15x}{x}\)
\(A(x)=\frac{0.15+18x}{x}\)
\(A(x)=\frac{0.15}{18+x}\)
\(A(x)=\frac{18+0.15x}{18+x}\)
\(A(x)=\frac{18}{x}+0.15\)
Solution
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Problem 2
The school band is in charge of a new set of uniforms made with a new logo. A local business charges $140 to set up the logo with the design and $0.25 in materials per logo printed. The function \(C(x)=\frac{140+0.25x}{x}\) represents the average cost per logo if \(x\) uniforms are printed by this business.
- What is the average cost per uniform to get the logo printed on 25 uniforms?
- What is the average cost per uniform to get the logo printed on 100 uniforms?
- How many uniforms should be printed to have an average cost of $1 per logo?
- What will happen to the price as the number of uniforms printed increases?
Solution
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Problem 3
Two competing sports equipment suppliers sell footballs at different prices. Supplier A charges $85 in shipping, and charges $2.59 per football. Supplier B charges $50 shipping, and charges $4.29 per football. A school wants to buy 40 balls. Which supplier has the lowest average cost per ball?
Solution
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Problem 4
What is one point of intersection between the graphs of the functions \(f(x)=(x + 6)(x+2)\) and \(g(x)=x+ 6\)?
\((0, 6)\)
\((\text-1, 5)\)
\((\text-2, 0)\)
\((\text-4,\text-4)\)
Solution
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(From Unit 2, Lesson 11.)Problem 5
The graph of a polynomial \(f(x)=(5x-3)(x+4)(x+a)\) has \(x\)-intercepts at -4, \(\frac35\), and 6. What is the value of \(a\)?
Solution
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(From Unit 2, Lesson 15.)Problem 6
The function \(f(x)=\frac{3x-4}{x+6}\) can be rewritten in the form \(f(x)=3+\frac{\text-22}{x+6}\). What is the end behavior of \(y=f(x)\)?
Solution
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(From Unit 2, Lesson 19.)