Math Problem Statement

Find the exponential function that is the best fit for​ f(x) defined by the table below.                                                                                                                        x 1 2 3 4 5

y 1 6 14 37 115

Solution

To find the exponential function f(x)=abxf(x) = a \cdot b^x that best fits the data provided, we will follow these steps:

  1. Formulate the model: Assume f(x)=abxf(x) = a \cdot b^x.
  2. Apply logarithmic transformation: To linearize the exponential model, we can take the natural logarithm of both sides, giving us: ln(y)=ln(a)+xln(b)\ln(y) = \ln(a) + x \cdot \ln(b) This transformation allows us to use linear regression on (x,ln(y))(x, \ln(y)) to find ln(a)\ln(a) and ln(b)\ln(b).
  3. Calculate values of ln(y)\ln(y) for each xx value: x=1,y=1ln(1)=0x = 1, y = 1 \Rightarrow \ln(1) = 0 x=2,y=6ln(6)1.79x = 2, y = 6 \Rightarrow \ln(6) \approx 1.79 x=3,y=14ln(14)2.64x = 3, y = 14 \Rightarrow \ln(14) \approx 2.64 x=4,y=37ln(37)3.61x = 4, y = 37 \Rightarrow \ln(37) \approx 3.61 x=5,y=115ln(115)4.74x = 5, y = 115 \Rightarrow \ln(115) \approx 4.74
  4. Perform linear regression on (x,ln(y))(x, \ln(y)) to determine the best fit line, from which we can extract ln(a)\ln(a) and ln(b)\ln(b).

Let's proceed with this approach to determine the values of aa and bb.The best-fit exponential function for f(x)f(x) based on the data provided is:

f(x)0.4343.098xf(x) \approx 0.434 \cdot 3.098^x

This model fits the data quite well, with an R2R^2 value of approximately 0.9820.982, indicating a strong correlation between the model and the data.

Would you like further details on the calculations or have any questions?

Related Questions

  1. How can I use this exponential function to estimate values of yy for other xx-values?
  2. What does the R2R^2 value indicate in terms of the model's accuracy?
  3. How would the approach differ if the data followed a linear rather than exponential trend?
  4. Can we use this function to predict values outside the provided range, and what are the limitations?
  5. How would a logarithmic function fit if the growth wasn't strictly exponential?

Tip

When estimating exponential growth, checking the fit with R2R^2 helps ensure accuracy and reveals how well the model captures the trend.

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Math Problem Analysis

Mathematical Concepts

Exponential Functions
Linear Regression
Logarithmic Transformation

Formulas

Exponential function form: f(x) = a * b^x
Logarithmic transformation: ln(y) = ln(a) + x * ln(b)
R-squared calculation for model fit

Theorems

Least Squares Method for Linear Regression

Suitable Grade Level

Grades 10-12