Math Problem Statement

Which function is positive for the entire interval [–3, –2]?

On a coordinate plane, a curved line with a minimum value of (0, negative 3) crosses the x-axis at (negative 3, 0) and (3, 0), and crosses the y-axis at (0, negative 3).

On a coordinate plane, a curved line with a minimum value of (2, negative 3) crosses the x-axis at (negative 1, 0) and (5, 0), and crosses the y-axis at (0, negative 1.5).

On a coordinate plane, a curved line with a minimum value of (2, 4) and a maximum value of (0.5, 6), crosses the x-axis at (negative 1.5, 0) and crosses the y-axis at (0, 5).

On a coordinate plane, a curved line with a minimum value of (negative 1.75, negative 3.9) and a maximum value of (0, 2), crosses the x-axis at (negative 2.2, 0), (negative 0.75, 0), and (0.75, 0), and crosses the y-axis at (0, 2).

Solution

To determine which function is positive for the entire interval [3,2][-3, -2], we need to analyze each described function and its behavior within this interval.

  1. Function with minimum value at (0, -3):

    • Crosses the x-axis at (3,0)(-3, 0) and (3,0)(3, 0)
    • Crosses the y-axis at (0,3)(0, -3)

    This function crosses the x-axis at (3,0)(-3, 0), so it is not positive for the entire interval [3,2][-3, -2].

  2. Function with minimum value at (2, -3):

    • Crosses the x-axis at (1,0)(-1, 0) and (5,0)(5, 0)
    • Crosses the y-axis at (0,1.5)(0, -1.5)

    This function has roots at (1,0)(-1, 0) and (5,0)(5, 0). Since [3,2][-3, -2] is to the left of the root (1,0)(-1, 0), we need to determine the sign of the function in this interval. Since the minimum value at (2, -3) indicates the function is negative around x=2x = 2 and crosses the x-axis at (1,0)(-1, 0), it is negative for [3,2][-3, -2].

  3. Function with minimum value at (2, 4) and maximum value at (0.5, 6):

    • Crosses the x-axis at (1.5,0)(-1.5, 0)
    • Crosses the y-axis at (0,5)(0, 5)

    This function crosses the x-axis at (1.5,0)(-1.5, 0). Since [3,2][-3, -2] is entirely to the left of this root and we know the function decreases towards this root, it is positive for [3,2][-3, -2].

  4. Function with minimum value at (-1.75, -3.9) and maximum value at (0, 2):

    • Crosses the x-axis at (2.2,0)(-2.2, 0), (0.75,0)(-0.75, 0), and (0.75,0)(0.75, 0)
    • Crosses the y-axis at (0,2)(0, 2)

    This function has a root at (2.2,0)(-2.2, 0). Since [3,2][-3, -2] includes the root (2.2,0)(-2.2, 0), the function is not positive for the entire interval [3,2][-3, -2].

Therefore, the function described in the third scenario is positive for the entire interval [3,2][-3, -2].

Would you like details on any specific function or have any further questions?

Here are some more questions you might want to ask:

  1. How to find the roots of a function?
  2. What is the significance of the minimum and maximum values in a function?
  3. How to determine the intervals where a function is positive or negative?
  4. How to analyze the behavior of a function using its graph?
  5. How do the coefficients of a polynomial function affect its graph?

Tip: When analyzing the behavior of functions, always check their critical points and where they cross the axes to understand their intervals of positivity or negativity.

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Math Problem Analysis

Mathematical Concepts

Functions
Interval Analysis
Roots of Functions

Formulas

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Theorems

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Suitable Grade Level

College Level