Math Problem Statement

X to the power of 4 - 3x to the power of 2 + 1 = 0. It has 4 real solutions, right? - radical 1.3, + radical 1.3, - radical 0.175 and + radical 0.175. If the test wanted me to write the 4 real solutions, wouldn't these 4 be the correct ones?

Solution

Let's solve the equation x43x2+1=0x^4 - 3x^2 + 1 = 0 to verify the solutions.

First, we can make a substitution to simplify the equation. Let y=x2y = x^2. Then the equation becomes: y23y+1=0y^2 - 3y + 1 = 0

This is a quadratic equation in yy. We can solve it using the quadratic formula y=b±b24ac2ay = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=1a = 1, b=3b = -3, and c=1c = 1: y=3±942y = \frac{3 \pm \sqrt{9 - 4}}{2} y=3±52y = \frac{3 \pm \sqrt{5}}{2}

So the solutions for yy are: y1=3+52y_1 = \frac{3 + \sqrt{5}}{2} y2=352y_2 = \frac{3 - \sqrt{5}}{2}

Recall that y=x2y = x^2, so we need to find the square roots of these solutions to get xx: x=±y1=±3+52x = \pm \sqrt{y_1} = \pm \sqrt{\frac{3 + \sqrt{5}}{2}} x=±y2=±352x = \pm \sqrt{y_2} = \pm \sqrt{\frac{3 - \sqrt{5}}{2}}

These are the four real solutions to the equation x43x2+1=0x^4 - 3x^2 + 1 = 0.

To compare with your solutions: 3+521.618\sqrt{\frac{3 + \sqrt{5}}{2}} \approx 1.618 3520.618\sqrt{\frac{3 - \sqrt{5}}{2}} \approx 0.618

Your solutions, ±1.3±1.14\pm \sqrt{1.3} \approx \pm 1.14 and ±0.175±0.42\pm \sqrt{0.175} \approx \pm 0.42, are not accurate. The correct solutions are:

±3+52±1.618\pm \sqrt{\frac{3 + \sqrt{5}}{2}} \approx \pm 1.618 ±352±0.618\pm \sqrt{\frac{3 - \sqrt{5}}{2}} \approx \pm 0.618

Therefore, the correct real solutions are: ±3+52\pm \sqrt{\frac{3 + \sqrt{5}}{2}} ±352\pm \sqrt{\frac{3 - \sqrt{5}}{2}}

Would you like more details on this solution or have any questions?

Here are 8 related questions to further explore the topic:

  1. How can we determine the roots of a polynomial equation in general?
  2. What is the significance of the quadratic formula in solving polynomial equations?
  3. Can all polynomial equations be solved by factoring?
  4. What are complex roots, and when do they occur?
  5. How do you verify if the obtained solutions are correct?
  6. What is the relationship between the degree of a polynomial and the number of its roots?
  7. Can you explain the process of completing the square for solving quadratic equations?
  8. How does Descartes' Rule of Signs help in determining the number of real roots of a polynomial?

Tip: When solving higher-degree polynomials, consider using substitution to reduce the equation to a simpler form, such as a quadratic equation. This can make finding the solutions more manageable.

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Math Problem Analysis

Mathematical Concepts

Polynomial Equations
Quadratic Equations
Root Finding

Formulas

Quadratic formula

Theorems

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Suitable Grade Level

High School