Math Problem Statement

Question 3

If function f(x) is f(x)= -3x^2+2x+1, which point does constitute a maximum or minimum of the function?

Solution

To determine whether the function f(x)=3x2+2x+1f(x) = -3x^2 + 2x + 1 has a maximum or minimum, we first need to find the vertex of the parabola described by the quadratic function.

Step 1: Identify the coefficients

The function is in the standard form of a quadratic equation, f(x)=ax2+bx+cf(x) = ax^2 + bx + c, where:

  • a=3a = -3
  • b=2b = 2
  • c=1c = 1

Step 2: Calculate the vertex

The x-coordinate of the vertex (which gives the maximum or minimum point) can be found using the formula:

x=b2ax = -\frac{b}{2a}

Substituting the values of aa and bb:

x=22(3)=26=13x = -\frac{2}{2(-3)} = \frac{2}{6} = \frac{1}{3}

Step 3: Find the y-coordinate of the vertex

To find the corresponding y-coordinate (which gives the value of f(x)f(x) at the vertex), substitute x=13x = \frac{1}{3} back into the function:

f(13)=3(13)2+2(13)+1f\left(\frac{1}{3}\right) = -3\left(\frac{1}{3}\right)^2 + 2\left(\frac{1}{3}\right) + 1

f(13)=3(19)+23+1=13+23+1=13+1=43f\left(\frac{1}{3}\right) = -3\left(\frac{1}{9}\right) + \frac{2}{3} + 1 = -\frac{1}{3} + \frac{2}{3} + 1 = \frac{1}{3} + 1 = \frac{4}{3}

Step 4: Determine if it's a maximum or minimum

Since the coefficient of x2x^2 (which is a=3a = -3) is negative, the parabola opens downwards. This means the vertex represents a maximum point.

Conclusion

The function f(x)=3x2+2x+1f(x) = -3x^2 + 2x + 1 has a maximum point at (13,43)\left(\frac{1}{3}, \frac{4}{3}\right).


Do you want more details on this process or have any questions?

Here are 5 related questions you might find interesting:

  1. How do you find the roots of the quadratic function f(x)=3x2+2x+1f(x) = -3x^2 + 2x + 1?
  2. What is the axis of symmetry for the function f(x)=3x2+2x+1f(x) = -3x^2 + 2x + 1?
  3. How would the vertex change if the function were f(x)=3x2+2x+1f(x) = 3x^2 + 2x + 1?
  4. How do you determine the nature of the roots of a quadratic function using the discriminant?
  5. Can you find the minimum or maximum value of a quadratic function without completing the square?

Tip: For any quadratic function f(x)=ax2+bx+cf(x) = ax^2 + bx + c, the sign of aa determines whether the vertex is a maximum (if a<0a < 0) or a minimum (if a>0a > 0).

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Maximum and Minimum Points

Formulas

Vertex formula for quadratic functions: x = -b/(2a)

Theorems

Quadratic function vertex theorem

Suitable Grade Level

Grades 9-12