Math Problem Statement

Tentukan nilai minimum dari fungsi f(x) = 2x^2 + 4x - 1

Solution

The question asks to determine the minimum value of the function f(x)=2x2+4x1f(x) = 2x^2 + 4x - 1.

This is a quadratic function, and the general form of a quadratic function is f(x)=ax2+bx+cf(x) = ax^2 + bx + c, where:

  • a=2a = 2
  • b=4b = 4
  • c=1c = -1

The minimum or maximum value of a quadratic function occurs at its vertex. For a parabola opening upwards (since a>0a > 0, it opens upwards), the vertex represents the minimum point.

The x-coordinate of the vertex is given by the formula: x=b2ax = \frac{-b}{2a} Substituting the values of aa and bb: x=42(2)=44=1x = \frac{-4}{2(2)} = \frac{-4}{4} = -1

Now, substitute x=1x = -1 into the function f(x)f(x) to find the minimum value of the function: f(1)=2(1)2+4(1)1=2(1)41=241=3f(-1) = 2(-1)^2 + 4(-1) - 1 = 2(1) - 4 - 1 = 2 - 4 - 1 = -3

Therefore, the minimum value of the function is 3-3.

It seems like the correct answer isn't listed in the given options. Let me know if you need further clarification or have any questions!

Follow-up Questions:

  1. What does the vertex formula represent in a quadratic function?
  2. How do we determine if a quadratic function has a minimum or maximum value?
  3. Why does the function f(x)=2x2+4x1f(x) = 2x^2 + 4x - 1 have a minimum rather than a maximum?
  4. How can we rewrite the function f(x)f(x) to complete the square and find its minimum value?
  5. What are the applications of finding the minimum or maximum value in real-life situations?

Tip:

For any quadratic function, if a>0a > 0, the function opens upwards, and the vertex gives the minimum value. If a<0a < 0, the vertex gives the maximum value.

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Algebra

Formulas

x = -b / 2a (vertex formula)
Quadratic function f(x) = ax^2 + bx + c

Theorems

The vertex of a parabola
The sign of 'a' determines whether the parabola opens upwards or downwards

Suitable Grade Level

Grades 10-11