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Mariah started to find the solutions of [tex]$x^2 + 4x + 1 = 0$[/tex]. Her work is shown below:

[tex]\[
\begin{array}{l}
x^2 + 4x + 1 = 0 \\
x^2 + 4x = -1 \\
x^2 + 4x + 4 = -1 + 4 \\
(x + 2)^2 = 3
\end{array}
\][/tex]

Which describes the solutions of the equation?

A. Since -2 and 3 are both rational, the sum and difference are rational.
B. Since -2 and [tex]$\sqrt{3}$[/tex] are both rational, the sum and difference are rational.
C. Since -2 is rational and [tex]$\sqrt{3}$[/tex] is irrational, the sum and difference are irrational.
D. Since [tex]$\sqrt{2}$[/tex] is rational and [tex]$\sqrt{3}$[/tex] is irrational, the sum and difference are irrational.


Sagot :

Let's analyze Mariah's work and understand the nature of the solutions step-by-step.

Mariah started with the quadratic equation:
[tex]\[ x^2 + 4x + 1 = 0 \][/tex]

1. She rearranged it to:
[tex]\[ x^2 + 4x = -1 \][/tex]

2. Next, she completed the square:
[tex]\[ x^2 + 4x + 4 = -1 + 4 \][/tex]

3. This simplification led to:
[tex]\[ (x + 2)^2 = 3 \][/tex]

To solve for [tex]\( x \)[/tex], take the square root of both sides:
[tex]\[ x + 2 = \pm \sqrt{3} \][/tex]

Then solve for [tex]\( x \)[/tex]:
[tex]\[ x = -2 \pm \sqrt{3} \][/tex]

So, the solutions to the equation [tex]\( x^2 + 4x + 1 = 0 \)[/tex] are:
[tex]\[ x = -2 + \sqrt{3} \quad \text{and} \quad x = -2 - \sqrt{3} \][/tex]

Now, let's analyze the nature of these solutions:

- [tex]\(-2\)[/tex] is a rational number.
- [tex]\(\sqrt{3}\)[/tex] is an irrational number.

For the sum and difference of these types of numbers:
- The sum of a rational number and an irrational number is always irrational.
- The difference between a rational number and an irrational number is always irrational.

Thus, the solutions [tex]\(-2 + \sqrt{3}\)[/tex] and [tex]\(-2 - \sqrt{3}\)[/tex] are both irrational because they consist of a rational part ([tex]\(-2\)[/tex]) and an irrational part ([tex]\(\sqrt{3}\)[/tex]).

Hence, the correct description of the solutions is:

Since -2 is rational and [tex]\(\sqrt{3}\)[/tex] is irrational, the sum and difference are irrational.