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Subsection 1.5 Solving Rational Equations Exercises

  1. Refer to \(P(x)=\frac{2}{4x-9}\) and \(S(x)=-\frac{x}{x-1}\text{.}\)
    1. What is the domain of \(P(x)\text{?}\)
    2. Graph \(P(x)\) so that the important features are visible, and label them.
    3. What is the domain of \(S(x)\text{?}\)
    4. Graph \(S(x)\) on the same set of axes as \(P(x)\text{.}\) Be sure that the important features are visible, and label them.
    5. Find the solutions to \(P(x)=S(x)\) using the graph on Desmos.
    6. Verify your solutions to \(P(x)=S(x)\) using algebra.
    7. Use your graph to solve \(P(x) \leq S(x)\text{.}\)
  2. Solve each equation.
    1. \(\displaystyle \frac{3}{k}=\frac{1}{k^2}+\frac{k+4}{k^2}\)
    2. \(\displaystyle 1=\frac{a-2}{4a}-\frac{1}{4a}\)
    3. \(\displaystyle \frac{3}{2m+8}=\frac{1}{m}-\frac{1}{2m^2+8m}\)
    4. \(\displaystyle \frac{1}{x^2-10x+24}+\frac{1}{x-4}=\frac{5}{x^2-10x+24}\)
    5. \(\displaystyle \frac{1}{2}=\frac{v+6}{2v-12}+\frac{3}{2}\)
  3. Supreme Scream is a ride in which passengers are dropped and experience the acceleration of gravity, before being rapidly brought to a complete stop. The ride reaches a height of 76.8 meters. An object falling under the force of gravity has height modeled by the equation \(H(t)=-4.9t^2 + vt + h\text{,}\) where \(H\) is measured in meters, \(v\) is the initial velocity in meters/second, and \(h\) is the initial height in meters.
    1. Keeping in mind that the ride drops passengers from a stop, write a function equation to model the height of passengers as a function of time since the ride started.
    2. If riders are allowed to free fall for 10 meters before the brakes are applied, how long (in seconds) is the free fall portion of the ride?
    3. If the speed of passengers on the ride is given by the equation \(S(t)=9.8t\) (meters/second), how fast are passengers traveling at the moment when the brakes are first applied?
    4. Suppose you are designing the next generation version of the ride, and you want riders to experience speeds of 80 miles/hour. How many meters must riders be allowed to free fall to reach this speed? (1 meter/second is the same as 2.24 miles/hour.)
  4. Refer to the function \(G(x)=\frac{3x^2-3}{(x-4)(x^2+1)}\text{.}\)
    1. Graph \(G(x)\) so that the important features are visible, and label them.
    2. Let \(H(x)=\frac{3x^2-3}{(x-4)(x^2-4)}\text{.}\) Graph \(H(x)\) so that the important features are visible, and label them.
    3. Explain why the graph of \(G\) has only one vertical asymptote, while \(H\) has three vertical asymptotes.
    4. What is the domain of \(G(x)\text{?}\)
    5. On which interval(s) is \(G(x)\) decreasing?
    6. What is the average rate of change of \(G(x)\) on the interval \(5 \leq x \leq 8\text{?}\)
    7. Let \(F(x)=G(x-2)\text{.}\) Graph \(F(x)\) and label its features.
  5. The population of Nairobi in Kenya was 2.14 million in 1999, and 3.14 million in 2009.
    1. Write a function equation \(P(t)\) for the number of people living in Nairobi \(t\) years after 1999.
    2. Rewrite \(P(t)\) using the natural base, \(e\text{.}\)
    3. What is the average number of additional residents added to Nairobi each year between 1999 and 2009?
    4. What will the population be in 2020, assuming it continues to grow at the same rate?
    5. When will the number of people living in Nairobi reach 5 million? First give an exact answer, and then give a decimal approximation.
  6. Solve the following equations.
    1. \(\displaystyle 2 \cdot 3^{x+4} = 162\)
    2. \(\displaystyle 64^{w-2}-\frac{1}{24}=\frac{1}{48}\)
    3. \(\displaystyle \ln (t+8) - \ln (t+13) = - \ln (2)\)