Chapter 8: Problem 117
Roller Coasters. The polynomial function \(f(x)=0.001 x^{3}-0.12 x^{2}+3.6 x+10\) models the path of a portion of the track of a roller coaster. Use the function equation to find the height of the track for \(x=0,20,40,\) and 60.
Short Answer
Expert verified
The heights at \(x = 0, 20, 40,\) and \(60\) are 10, 42, 26, and 10 respectively.
Step by step solution
01
Substitute and Calculate for x=0
To find the height of the track at \(x = 0\), substitute \(x = 0\) into the function \(f(x) = 0.001x^3 - 0.12x^2 + 3.6x + 10\). \[ f(0) = 0.001(0)^3 - 0.12(0)^2 + 3.6(0) + 10 = 10 \]Thus, the height of the track at \(x = 0\) is 10.
02
Substitute and Calculate for x=20
Next, substitute \(x = 20\) into the function to find the height of the track at this point.\[ f(20) = 0.001(20)^3 - 0.12(20)^2 + 3.6(20) + 10 \]Calculate each term:- \(0.001 imes 8000 = 8\)- \(-0.12 imes 400 = -48\)- \(3.6 imes 20 = 72\)Combine these results:\[ f(20) = 8 - 48 + 72 + 10 = 42 \]The height at \(x = 20\) is 42.
03
Substitute and Calculate for x=40
Now calculate for \(x = 40\):\[ f(40) = 0.001(40)^3 - 0.12(40)^2 + 3.6(40) + 10 \]Calculate each term:- \(0.001 imes 64000 = 64\)- \(-0.12 imes 1600 = -192\)- \(3.6 imes 40 = 144\)Combine these results:\[ f(40) = 64 - 192 + 144 + 10 = 26 \]The height at \(x = 40\) is 26.
04
Substitute and Calculate for x=60
Finally, substitute \(x = 60\) into the function:\[ f(60) = 0.001(60)^3 - 0.12(60)^2 + 3.6(60) + 10 \]Calculate each term:- \(0.001 imes 216000 = 216\)- \(-0.12 imes 3600 = -432\)- \(3.6 imes 60 = 216\)Combine these results:\[ f(60) = 216 - 432 + 216 + 10 = 10 \]The height at \(x = 60\) is 10.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Roller Coaster Path Modeling
Modeling the path of a roller coaster using a polynomial function is an exciting way to visualize the fun and thrilling world of amusement park rides. In essence, each term in the polynomial function represents a different aspect of the track's shape and how it changes as you move along the x-axis. The given polynomial for our problem is: \[ f(x) = 0.001x^3 - 0.12x^2 + 3.6x + 10 \]
- The term \(0.001x^3\) affects the curvature, making the track bend upwards or downwards.
- The term \(-0.12x^2\) contributes to the steepness and direction, moving the track in a different curvature compared to the cubic term.
- The linear term \(3.6x\) indicates a slope, which directly influences the incline or decline of the track.
- The constant \(10\) adjusts the starting height of the roller coaster.
Substitution Method
The substitution method is a straightforward technique utilized for calculating the value of a function at a specific point. You essentially replace the variable in the function with a given number. This is precisely what was applied in the task for different values of \(x\).For instance, to find the height of the track when \(x=20\):1. Substitute \(x=20\) into the polynomial: \[ f(20) = 0.001(20)^3 - 0.12(20)^2 + 3.6(20) + 10 \] 2. Calculate each component step-by-step: - The cube of 20 is multiplied by 0.001, resulting in 8. - The square of 20 is multiplied by -0.12, giving -48. - And 20 times 3.6 equals 72.3. Add these results together along with the constant: \[ 8 - 48 + 72 + 10 = 42 \]Using the substitution method is handy because it simplifies one component at a time, reducing the risks of mistakes. This approach is vital for students learning to handle not only simple problems but also complex polynomials in both academics and real-life applications, like roller coaster design.
Polynomial Evaluation
Evaluating a polynomial function involves finding the result of the polynomial at specific input values, which was demonstrated in the original solution through various x-values. To grasp the concept, consider evaluating the polynomial:\[ f(x) = 0.001x^3 - 0.12x^2 + 3.6x + 10 \]To evaluate it at \(x=40\), break it down:
- Calculate the cube of 40 and multiply it by 0.001, resulting in 64.
- Calculate the square of 40 and multiply it by -0.12, resulting in -192.
- Multiply 40 by 3.6 to get 144.
- Add those terms to the constant 10.