Math Problem Statement

Find an equation for the graph shown on a semi-logarithmic scale, where the y-axis represents log(y) and the graph displays a straight line.

Solution

To find the equation for the given graph on a semi-logarithmic scale, let's analyze the information.

Understanding the Semi-Log Scale

The yy-axis is labeled as log(y)\log(y), indicating that this is a semi-logarithmic plot, where:

  • The xx-axis is in a linear scale.
  • The yy-axis represents log(y)\log(y), meaning each unit on the yy-axis corresponds to an exponential increase in yy.

This suggests the function is of the form: y=abxy = a \cdot b^x where log(y)=log(a)+xlog(b)\log(y) = \log(a) + x \cdot \log(b), and thus, the graph of log(y)\log(y) versus xx should be a straight line.

Analyzing the Line

On the graph:

  1. Identify two points on the line, as we need them to determine the slope and intercept.

    • Looking at the image, the line seems to pass through points approximately at (0,3)(0, -3) and (2,2)(2, -2).
  2. Using these points, calculate the slope mm: m=2(3)20=12m = \frac{-2 - (-3)}{2 - 0} = \frac{1}{2}

  3. The equation of the line in terms of log(y)\log(y) is: log(y)=12x3\log(y) = \frac{1}{2}x - 3

Converting to Exponential Form

Now, rewrite this in terms of yy:

  1. Recall that log(y)=12x3\log(y) = \frac{1}{2}x - 3.
  2. Converting from logarithmic to exponential form: y=1012x3y = 10^{\frac{1}{2}x - 3}
  3. Simplify: y=1031012x=(103)(1012)xy = 10^{-3} \cdot 10^{\frac{1}{2}x} = \left(10^{-3}\right) \cdot \left(10^{\frac{1}{2}}\right)^x
  4. Thus, a=103a = 10^{-3} and b=1012b = 10^{\frac{1}{2}}.

So, the final equation is: y(x)=0.001(100.5)xy(x) = 0.001 \cdot (10^{0.5})^x

Let me know if you'd like more details or if you have questions about any part of the solution!


Here are 5 related questions to expand your understanding:

  1. How does a semi-log scale differ from a log-log scale?
  2. What types of real-world data are best represented by exponential functions?
  3. How would the slope change if the function’s growth rate increased?
  4. Why is the y-axis in log scale rather than linear scale for this graph?
  5. How do we interpret the intercept in an exponential function on a semi-log scale?

Tip: When working with semi-log scales, keep in mind that the line's slope represents the growth rate of the exponential function.

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Math Problem Analysis

Mathematical Concepts

Semi-logarithmic Scale
Exponential Functions
Logarithmic Conversion

Formulas

y = a * b^x
log(y) = log(a) + x * log(b)

Theorems

Exponential Growth Theorem
Logarithmic Properties

Suitable Grade Level

Grades 10-12