Given the equation [tex]-4 \sqrt{x-3}=-12[/tex], solve for [tex]x[/tex] and identify if it is an extraneous solution.

A. [tex]x=0[/tex], solution is extraneous
B. [tex]x=0[/tex], solution is not extraneous
C. [tex]x=12[/tex], solution is extraneous
D. [tex]x=12[/tex], solution is not extraneous



Answer :

To solve the equation [tex]\( -4 \sqrt{x - 3} = -12 \)[/tex] for [tex]\( x \)[/tex], we will follow a step-by-step approach.

1. Isolate the square root term:

The given equation is:
[tex]\[ -4 \sqrt{x - 3} = -12 \][/tex]

First, we can divide both sides of the equation by [tex]\(-4\)[/tex] to isolate the square root term:
[tex]\[ \sqrt{x - 3} = \frac{-12}{-4} \][/tex]

Simplifying the right side, we get:
[tex]\[ \sqrt{x - 3} = 3 \][/tex]

2. Remove the square root by squaring both sides:

To eliminate the square root, we square both sides of the equation:
[tex]\[ (\sqrt{x - 3})^2 = 3^2 \][/tex]

Simplifying both sides:
[tex]\[ x - 3 = 9 \][/tex]

3. Solve for [tex]\( x \)[/tex]:

Add 3 to both sides to solve for [tex]\( x \)[/tex]:
[tex]\[ x = 9 + 3 \][/tex]

Simplifying the right side:
[tex]\[ x = 12 \][/tex]

So the potential solution is:
[tex]\[ x = 12 \][/tex]

4. Check for extraneous solutions:

To check if [tex]\( x = 12 \)[/tex] is an extraneous solution, substitute [tex]\( x = 12 \)[/tex] back into the original equation:
[tex]\[ -4 \sqrt{12 - 3} = -12 \][/tex]

Simplify inside the square root:
[tex]\[ -4 \sqrt{9} = -12 \][/tex]

Simplify the square root:
[tex]\[ -4 \cdot 3 = -12 \][/tex]

Which simplifies to:
[tex]\[ -12 = -12 \][/tex]

As the left side equals the right side, [tex]\( x = 12 \)[/tex] satisfies the original equation and is not an extraneous solution.

Therefore, the correct answer is:
[tex]\[ x = 12, \text{ solution is not extraneous} \][/tex]