Math Problem Statement

f(x)=2x^2+2x

Solution

The function given is:

f(x)=2x2+2xf(x) = 2x^2 + 2x

This is a quadratic function in terms of xx. Let's analyze its key properties:

1. Standard Form:

The function is already in standard form for a quadratic equation:

f(x)=ax2+bx+cf(x) = ax^2 + bx + c

where a=2a = 2, b=2b = 2, and c=0c = 0.

2. Vertex Form:

To find the vertex form of the quadratic function, we can complete the square:

f(x)=2x2+2xf(x) = 2x^2 + 2x

Factor out the 2 from the first two terms:

f(x)=2(x2+x)f(x) = 2(x^2 + x)

To complete the square inside the parentheses, take half of the coefficient of xx (which is 1), square it (resulting in (12)2=14\left(\frac{1}{2}\right)^2 = \frac{1}{4}), and add and subtract it inside the parentheses:

f(x)=2(x2+x+1414)f(x) = 2\left(x^2 + x + \frac{1}{4} - \frac{1}{4}\right)

This simplifies to:

f(x)=2((x+12)214)f(x) = 2\left( (x + \frac{1}{2})^2 - \frac{1}{4} \right)

Distribute the 2:

f(x)=2(x+12)212f(x) = 2(x + \frac{1}{2})^2 - \frac{1}{2}

The vertex form is:

f(x)=2(x+12)212f(x) = 2(x + \frac{1}{2})^2 - \frac{1}{2}

Here, the vertex of the parabola is at (12,12)\left(-\frac{1}{2}, -\frac{1}{2}\right).

3. Axis of Symmetry:

The axis of symmetry for a parabola in the form ax2+bx+cax^2 + bx + c is given by:

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

Substituting the values of a=2a = 2 and b=2b = 2:

x=222=12x = -\frac{2}{2 \cdot 2} = -\frac{1}{2}

So, the axis of symmetry is x=12x = -\frac{1}{2}.

4. Y-Intercept:

The y-intercept occurs when x=0x = 0:

f(0)=2(0)2+2(0)=0f(0) = 2(0)^2 + 2(0) = 0

So, the y-intercept is at (0,0)(0, 0).

5. Roots (X-Intercepts):

To find the roots, set f(x)=0f(x) = 0:

2x2+2x=02x^2 + 2x = 0

Factor out the common term:

2x(x+1)=02x(x + 1) = 0

Set each factor to zero:

  1. 2x=0    x=02x = 0 \implies x = 0
  2. x+1=0    x=1x + 1 = 0 \implies x = -1

So, the roots are x=0x = 0 and x=1x = -1.

Would you like more details on any of these points, or do you have any questions?

Relative Questions:

  1. What is the significance of the vertex of a parabola in a quadratic function?
  2. How do you derive the vertex form of a quadratic function from its standard form?
  3. How can the roots of a quadratic function be interpreted graphically?
  4. What is the role of the axis of symmetry in a quadratic function?
  5. How does the coefficient aa affect the shape and direction of a parabola?

Tip:

When converting a quadratic function to vertex form, remember that completing the square is a powerful technique for identifying the vertex and understanding the graph's properties better.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Graphing

Formulas

Standard form of a quadratic equation ax^2 + bx + c
Vertex form of a quadratic function
Axis of symmetry formula x = -b/2a

Theorems

Completing the Square
Quadratic Formula

Suitable Grade Level

Grades 8-10