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Find all real solutions of the quadratic equation. $$x^{2}-\sqrt{5} x+1=0$$

Short Answer

Expert verified
The real solutions are \(x_1 = \frac{\sqrt{5} + 1}{2}\) and \(x_2 = \frac{\sqrt{5} - 1}{2}\).

Step by step solution

01

Identify the quadratic equation

The given quadratic equation is \(x^2 - \sqrt{5}x + 1 = 0\). This can be compared to the standard form \(ax^2 + bx + c = 0\) where \(a = 1\), \(b = -\sqrt{5}\), and \(c = 1\).
02

Use the quadratic formula

To find the solutions for \(x\), use the quadratic formula: \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\). Plugging in the values from the equation, \(a = 1\), \(b = -\sqrt{5}\), and \(c = 1\).
03

Calculate the discriminant

We begin by calculating the discriminant \(b^2 - 4ac\). Here it is: \((-\sqrt{5})^2 - 4(1)(1) = 5 - 4 = 1\). Since the discriminant is positive, there are two real solutions.
04

Solve for the roots

Substitute the discriminant and values of \(a\) and \(b\) into the quadratic formula: \(x = \frac{-(-\sqrt{5}) \pm \sqrt{1}}{2 \cdot 1}\). Simplifying, \(x = \frac{\sqrt{5} \pm 1}{2}\).
05

Express the solutions

The two solutions are \(x_1 = \frac{\sqrt{5} + 1}{2}\) and \(x_2 = \frac{\sqrt{5} - 1}{2}\). These are the real solutions of the quadratic equation.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Quadratic Formula
To solve quadratic equations like the one given, \(x^2 - \sqrt{5}x + 1 = 0\), we often use a powerful tool known as the quadratic formula. The quadratic formula is applicable to any quadratic equation in the standard form \(ax^2 + bx + c = 0\). By substituting a, b, and c from our equation into the formula:
  • \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\)
You can determine the values of \(x\), which are the solutions of the equation. In this formula:
  • \(a\) is the coefficient of \(x^2\)
  • \(b\) is the coefficient of \(x\)
  • \(c\) is the constant term
For our particular equation, we have \(a = 1\), \(b = -\sqrt{5}\), and \(c = 1\). Substituting these into the quadratic formula allows us to move to discriminant calculation.
Real Solutions
Determining whether a quadratic equation has real solutions depends on the value of the discriminant. The discriminant is a part of the quadratic formula under the square root, \(b^2 - 4ac\). The value of the discriminant tells us:
  • If \(b^2 - 4ac > 0\), there are two distinct real solutions.
  • If \(b^2 - 4ac = 0\), there is exactly one real solution, sometimes called a double root.
  • If \(b^2 - 4ac < 0\), the equation does not have real solutions but rather two complex solutions.
In the equation \(x^2 - \sqrt{5}x + 1 = 0\), the discriminant was calculated to be 1 which is greater than 0. This result confirms that the equation has two distinct real solutions.
Discriminant Calculation
Calculating the discriminant is a crucial step in the process of solving quadratic equations. The discriminant formula is given by \(b^2 - 4ac\). For our equation, rewinding to the values \(a = 1\), \(b = -\sqrt{5}\), and \(c = 1\), let's calculate this step by step:

Step-by-step Calculation

- Firstly, compute \((-\sqrt{5})^2\) which results in 5.- Then, calculate \(4 \, \cdot \, 1 \, \cdot \, 1\), which equals 4.- Subtracting these gives you the discriminant: \(5 - 4 = 1\).This positive discriminant value tells us that the quadratic equation will have two real solutions. This process ensures a clear understanding of the nature of the roots without even solving for them directly.

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