Math Problem Statement

Δίνεται η συνάρτηση f(x) = 4x^3 - 6x^2 + 2x. i. Να αποδώσετε τη συνάρτηση f(x) ως γινόμενο πρώτων παραγόντων. ii. Να λύσετε την εξίσωση f(x) = 0. iii. Δίνεται η συνάρτηση h(x) = 2x^2 - 3x - 9. Να βρείτε τις τιμές του x για τις οποίες ισχύει ότι h(x) < 1.

Solution

Let's solve the given problems step by step:

Given:

f(x)=4x36x2+2xf(x) = 4x^3 - 6x^2 + 2x

i. Express f(x)f(x) as a product of its first derivatives.

To find the derivative of f(x)f(x): f(x)=ddx(4x36x2+2x)=12x212x+2f'(x) = \frac{d}{dx}(4x^3 - 6x^2 + 2x) = 12x^2 - 12x + 2

Now, let's try to factorize f(x)f(x) using common factors: f(x)=2x(2x23x+1)f(x) = 2x(2x^2 - 3x + 1)

The quadratic can be further factorized: 2x(2x23x+1)=2x(2x1)(x1)2x(2x^2 - 3x + 1) = 2x(2x - 1)(x - 1)

So, the factorized form of f(x)f(x) is: f(x)=2x(2x1)(x1)f(x) = 2x(2x - 1)(x - 1)

ii. Solve the equation f(x)=0f(x) = 0.

Using the factorized form: 2x(2x1)(x1)=02x(2x - 1)(x - 1) = 0

Setting each factor equal to zero gives:

  • 2x=0x=02x = 0 \Rightarrow x = 0
  • 2x1=0x=122x - 1 = 0 \Rightarrow x = \frac{1}{2}
  • x1=0x=1x - 1 = 0 \Rightarrow x = 1

So, the solutions are: x=0,x=12,x=1x = 0, \quad x = \frac{1}{2}, \quad x = 1

iii. Given h(x)=2x23x9h(x) = 2x^2 - 3x - 9. Find the values of xx for which h(x)<1h(x) < 1.

We need to solve: 2x23x9<12x^2 - 3x - 9 < 1 2x23x10<02x^2 - 3x - 10 < 0

Let's find the roots of the quadratic equation 2x23x10=02x^2 - 3x - 10 = 0 using the quadratic formula: x=(3)±(3)242(10)22x = \frac{-(-3) \pm \sqrt{(-3)^2 - 4 \cdot 2 \cdot (-10)}}{2 \cdot 2} x=3±9+804x = \frac{3 \pm \sqrt{9 + 80}}{4} x=3±894x = \frac{3 \pm \sqrt{89}}{4}

The approximate solutions are: x1=3894andx2=3+894x_1 = \frac{3 - \sqrt{89}}{4} \quad \text{and} \quad x_2 = \frac{3 + \sqrt{89}}{4}

Since this is a parabola opening upwards (coefficient of x2x^2 is positive), the inequality 2x23x10<02x^2 - 3x - 10 < 0 holds between the roots: 3894<x<3+894\frac{3 - \sqrt{89}}{4} < x < \frac{3 + \sqrt{89}}{4}

Would you like a more detailed explanation of any part? Here are some related questions to explore:

  1. How do you factor polynomials?
  2. What is the quadratic formula and how is it used?
  3. How do you determine intervals for which a quadratic inequality is satisfied?
  4. What is the relationship between the derivative and the factorization of a polynomial?
  5. How can you graphically represent the solution to an inequality?

Tip: When solving inequalities involving quadratic expressions, remember to find the roots and test intervals between them.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomials
Derivatives
Quadratic Equations
Inequalities

Formulas

Derivative formula: f'(x) = d/dx[f(x)]
Quadratic equation: ax^2 + bx + c = 0
Factoring polynomials
Inequality solution techniques

Theorems

Quadratic formula: x = [-b ± sqrt(b^2 - 4ac)] / 2a
Factor theorem for polynomials
Properties of parabolas

Suitable Grade Level

Grades 10-12