Math Problem Statement

Determine whether the given tables of values represent a quadratic function, and state the reason if not.

Solution

In the image provided, the task is to determine whether the given tables of values represent a quadratic function. There are four tables labeled as (4), (3), (2), and (1), with x and y values listed.

To check if the tables represent a quadratic function:

A quadratic function will have a constant second difference between the y values when the x values are equally spaced. Here's the process:

  1. Find the first differences between consecutive y values.
  2. Find the second differences (the difference between consecutive first differences).

If the second differences are constant, the function is quadratic. Let's evaluate each table:


Table (4):

  • x values: -1, 0, 1, 2
  • y values: 5, 10, 15, 20

First differences:

  • 105=510 - 5 = 5
  • 1510=515 - 10 = 5
  • 2015=520 - 15 = 5

Second differences:

  • 55=05 - 5 = 0
  • 55=05 - 5 = 0

Since the second differences are zero, this is not a quadratic function.


Table (3):

  • x values: -7, -6, -5, -4, -3
  • y values: 43, 31, 21, 13, 7

First differences:

  • 3143=1231 - 43 = -12
  • 2131=1021 - 31 = -10
  • 1321=813 - 21 = -8
  • 713=67 - 13 = -6

Second differences:

  • 10(12)=2-10 - (-12) = 2
  • 8(10)=2-8 - (-10) = 2
  • 6(8)=2-6 - (-8) = 2

Since the second differences are constant (2), this is a quadratic function.


Table (2):

  • x values: 0, 1, 2, 3
  • y values: 30, 124, 342, 728

First differences:

  • 12430=94124 - 30 = 94
  • 342124=218342 - 124 = 218
  • 728342=386728 - 342 = 386

Second differences:

  • 21894=124218 - 94 = 124
  • 386218=168386 - 218 = 168

Since the second differences are not constant, this is not a quadratic function.


Table (1):

  • x values: -3, -2, -1, 0, 1
  • y values: 12, 6, 2, 0, 0

First differences:

  • 612=66 - 12 = -6
  • 26=42 - 6 = -4
  • 02=20 - 2 = -2
  • 00=00 - 0 = 0

Second differences:

  • 4(6)=2-4 - (-6) = 2
  • 2(4)=2-2 - (-4) = 2
  • 0(2)=20 - (-2) = 2

Since the second differences are constant (2), this is a quadratic function.


Summary:

  • Table (4): Not quadratic.
  • Table (3): Quadratic.
  • Table (2): Not quadratic.
  • Table (1): Quadratic.

Would you like more details or further explanation on any step?


Here are some follow-up questions:

  1. How can you confirm whether a function is quadratic using its equation?
  2. What is the significance of second differences being constant?
  3. Can you provide another example of a quadratic table and solve it?
  4. How does a cubic function differ from a quadratic function in terms of differences?
  5. What are the graphical characteristics of quadratic functions?

Tip: Always double-check second differences when determining if a function is quadratic—it’s an essential indicator!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
First and Second Differences

Formulas

First Differences = y2 - y1
Second Differences = first difference2 - first difference1

Theorems

If the second differences are constant, the function is quadratic.

Suitable Grade Level

Grades 9-10