Which of the following is an extraneous solution of [tex]\sqrt{-3x-2} = x + 2[/tex]?

A. [tex]x = -6[/tex]

B. [tex]x = -1[/tex]

C. [tex]x = 1[/tex]

D. [tex]x = 6[/tex]



Answer :

To solve the equation [tex]\(\sqrt{-3x - 2} = x + 2\)[/tex], we must identify any extraneous solutions. Let's start by solving the equation and then check each proposed solution.

### Step-by-Step Solution:

1. Square both sides of the equation to eliminate the square root:
[tex]\[ (\sqrt{-3x - 2})^2 = (x + 2)^2 \][/tex]
This simplifies to:
[tex]\[ -3x - 2 = (x + 2)^2 \][/tex]

2. Expand the right-hand side of the equation:
[tex]\[ (x + 2)^2 = x^2 + 4x + 4 \][/tex]
So, the equation becomes:
[tex]\[ -3x - 2 = x^2 + 4x + 4 \][/tex]

3. Rearrange the equation to form a standard quadratic equation:
[tex]\[ 0 = x^2 + 4x + 4 + 3x + 2 \][/tex]
Combine like terms:
[tex]\[ x^2 + 7x + 6 = 0 \][/tex]

4. Factor the quadratic equation:
[tex]\[ x^2 + 7x + 6 = (x + 1)(x + 6) = 0 \][/tex]
This gives us two potential solutions:
[tex]\[ x + 1 = 0 \quad \text{or} \quad x + 6 = 0 \][/tex]
So:
[tex]\[ x = -1 \quad \text{or} \quad x = -6 \][/tex]

### Checking for Extraneous Solutions:
We need to check each solution to see if it satisfies the original equation [tex]\(\sqrt{-3x - 2} = x + 2\)[/tex]:

1. Check [tex]\(x = -1\)[/tex]:
[tex]\[ \sqrt{-3(-1) - 2} = \sqrt{3 - 2} = \sqrt{1} = 1 \][/tex]
[tex]\[ -1 + 2 = 1 \][/tex]
Since both sides equal 1, [tex]\(x = -1\)[/tex] is a valid solution.

2. Check [tex]\(x = -6\)[/tex]:
[tex]\[ \sqrt{-3(-6) - 2} = \sqrt{18 - 2} = \sqrt{16} = 4 \][/tex]
[tex]\[ -6 + 2 = -4 \][/tex]
Since [tex]\(\sqrt{16} = 4\)[/tex] does not equal [tex]\(-4\)[/tex], [tex]\(x = -6\)[/tex] is an extraneous solution.

Given the original equation and the checks that we performed, the extraneous solution is:

[tex]\[ \boxed{x = -6} \][/tex]