Chapter 3: Problem 4
Graph each equation on your calculator, and trace to find the approximate \(y\)-value for the given \(x\)-value. a. \(y=1.21-x\) when \(x=70.2\) b. \(y=6.02+44.3 x\) when \(x=96.7\) c. \(y=-0.06+0.313 x\) when \(x=0.64\) d. \(y=1183-2140 x\) when \(x=-111\)
Short Answer
Expert verified
a. \( y = -68.99 \); b. \( y = 4297.23 \); c. \( y = 0.14032 \); d. \( y = 238723 \).
Step by step solution
01
Graph the Equation for a
Input the equation \( y = 1.21 - x \) into your graphing calculator. Ensure that you have the appropriate window settings to view the line on your screen.
02
Trace to Find y for x=70.2 in a
Use the trace function on your calculator to find the approximate value of \( y \) when \( x = 70.2 \). The calculator will help you find this by showing the intersection point on the graph.
03
Calculate y Directly for a
Instead of only relying on the trace function, you can directly compute by substituting \( x = 70.2 \) into the equation: \( y = 1.21 - 70.2 \).
04
Solve for y in a
Calculate the value: \( y = 1.21 - 70.2 = -68.99 \).
05
Graph the Equation for b
Input the equation \( y = 6.02 + 44.3x \) into your graphing calculator and ensure a wide enough window to clearly see the graph.
06
Trace to Find y for x=96.7 in b
Using the trace feature, find \( y \) when \( x = 96.7 \). Track the value on the calculator to get an accurate reading.
07
Calculate y Directly for b
Substitute \( x = 96.7 \) in the equation: \( y = 6.02 + 44.3 \times 96.7 \).
08
Solve for y in b
Calculate the value: \( y = 6.02 + 4291.21 = 4297.23 \).
09
Graph the Equation for c
Enter \( y = -0.06 + 0.313x \) into your calculator and make sure the window settings allow you to view the line.
10
Trace to Find y for x=0.64 in c
Use the trace function to find the approximate y-value for \( x = 0.64 \). Locate this value on the graph using the calculator.
11
Calculate y Directly for c
Substitute \( x = 0.64 \) into the equation: \( y = -0.06 + 0.313 \times 0.64 \).
12
Solve for y in c
Compute the expression: \( y = -0.06 + 0.20032 = 0.14032 \).
13
Graph the Equation for d
Input the equation \( y = 1183 - 2140x \) into your calculator and adjust the viewing window to visualize the line.
14
Trace to Find y for x=-111 in d
With the trace function, find \( y \) for \( x = -111 \). Follow the graph on the calculator screen for an accurate value.
15
Calculate y Directly for d
Substitute \( x = -111 \) into the equation: \( y = 1183 - 2140 \times (-111) \).
16
Solve for y in d
Compute the value: \( y = 1183 + 237540 = 238723 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Calculator Use
Using a graphing calculator to plot equations can simplify complex calculations and allow you to visualize results, making it easier to understand mathematical concepts. Calculators help:
- Quickly plot curves and lines based on input equations.
- Provide immediate results on whether your graph settings (like the window size) correctly display all relevant details of your graph.
- Experiment with changes dynamically to understand how different values or expressions affect the graph.
Trace Function
The trace function on a graphing calculator is a valuable tool for examining specific points on a graphed equation. It allows you to see coordinates at various points on the curve, helping you to find approximate values easily. The trace function helps:
- Locate particular y-values for specified x-values directly on the graph.
- Understand intersection points or other relevant points on complex graphs by following the plotted line.
- See how values change along the curve, which enhances comprehension of the graph's behavior.
Substitution Method
The substitution method is a straightforward algebraic approach to finding unknown values in equations. It's particularly useful when working alongside tools like calculators, as it verifies results from graphical analysis. Here’s how it helps:
- Directly calculate exact y-values by substituting known x-values into the equation.
- Offer a way to double-check results obtained from graphical trace outputs, ensuring accuracy.
- Enhance understanding of algebraic manipulations and their impact on variables.
Algebraic Expressions
Algebraic expressions form the backbone of modeling real-world scenarios through equations. Mastery of these expressions is essential for solving problems and facilitating calculations with tools like calculators. Understanding them helps:
- Recognize and manipulate different forms of expressions such as linear, quadratic, or polynomial.
- Translate practical situations into mathematical models to calculate unknowns logically.
- Develop strategies for solving equations, whether through graphical, substitution, or other algebraic methods.