Math Problem Statement

Look at this table: x y 1 3 7 2 9 14 3 27 28 4 81 56 5 243 112 Write a linear function (y=mx+b) or an exponential function (y=a(b)x) that models the data

Solution

Let's analyze the given table and determine whether a linear or exponential function best fits the data.

Given data:

xy1y2
137
2914
32728
48156
5243112

It appears that there are two sequences of yy-values corresponding to each xx-value.

Step 1: Check if one of the yy-values follows an exponential pattern:

  • Looking at the first column of y-values:
    3,9,27,81,2433, 9, 27, 81, 243 Each term is obtained by multiplying the previous term by 3: 3×3=9,9×3=27,27×3=81,81×3=2433 \times 3 = 9, \quad 9 \times 3 = 27, \quad 27 \times 3 = 81, \quad 81 \times 3 = 243 This follows the form: y=a(b)xy = a(b)^x Since the first value (when x=1x=1) is 33, we set a=3a = 3 and b=3b = 3, giving the function: y=3(3)xy = 3(3)^x

Step 2: Check if the second column of y-values follows a linear pattern:

  • The second sequence is: 7,14,28,56,1127, 14, 28, 56, 112 Checking the rate of change: 147=7,2814=14,5628=28,11256=5614 - 7 = 7, \quad 28 - 14 = 14, \quad 56 - 28 = 28, \quad 112 - 56 = 56 Since the differences are doubling rather than remaining constant, this is not linear but exponential.

    The pattern follows: 7,7(2),7(2)2,7(2)3,7(2)47, 7(2), 7(2)^2, 7(2)^3, 7(2)^4 This means: y=7(2)x1y = 7(2)^{x-1}

Final Answer:

  1. First function (exponential):
    y=3(3)xy = 3(3)^x
  2. Second function (exponential):
    y=7(2)x1y = 7(2)^{x-1}

Would you like a step-by-step breakdown of how I found these functions?

Related Questions:

  1. How do you determine if a function is linear or exponential?
  2. Can you convert an exponential function to a logarithmic form?
  3. What happens if an exponential function has a negative base?
  4. How can you find an exponential function given only two points?
  5. How do real-world applications use exponential functions (e.g., population growth, radioactive decay)?

Quick Tip:

To identify an exponential function, check if the ratio of consecutive terms is constant instead of their differences!

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Math Problem Analysis

Mathematical Concepts

Exponential Functions
Linear Functions
Rates of Change

Formulas

y = a(b)^x
y = mx + b

Theorems

Exponential Growth/Decay
Linear Functions

Suitable Grade Level

Grades 9-11