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If [tex]x - 12 \sqrt{x} + 36 = 0[/tex], what is the value of [tex]x[/tex]?

A. 6
B. [tex]6^2[/tex]
C. [tex]6^3[/tex]
D. [tex]6^4[/tex]


Sagot :

Let's solve the equation [tex]\(x - 12 \sqrt{x} + 36 = 0\)[/tex] step by step to find the value of [tex]\(x\)[/tex].

1. Start by setting the equation equal to zero:
[tex]\[ x - 12 \sqrt{x} + 36 = 0 \][/tex]

2. To simplify, let's make a substitution. Let [tex]\( y = \sqrt{x} \)[/tex]. Therefore, [tex]\( y^2 = x \)[/tex].

3. Substituting [tex]\( y \)[/tex] into the equation, we get:
[tex]\[ y^2 - 12y + 36 = 0 \][/tex]

4. This is a quadratic equation in [tex]\( y \)[/tex]. We can solve it using the quadratic formula [tex]\( y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)[/tex], where [tex]\( a = 1 \)[/tex], [tex]\( b = -12 \)[/tex], and [tex]\( c = 36 \)[/tex].

5. Let's apply the quadratic formula:
[tex]\[ y = \frac{-(-12) \pm \sqrt{(-12)^2 - 4 \cdot 1 \cdot 36}}{2 \cdot 1} \][/tex]
Simplify inside the square root:
[tex]\[ y = \frac{12 \pm \sqrt{144 - 144}}{2} \][/tex]
[tex]\[ y = \frac{12 \pm \sqrt{0}}{2} \][/tex]
[tex]\[ y = \frac{12 \pm 0}{2} \][/tex]
[tex]\[ y = \frac{12}{2} \][/tex]
[tex]\[ y = 6 \][/tex]

6. Recall that [tex]\( y = \sqrt{x} \)[/tex]. Substituting back, we have:
[tex]\[ \sqrt{x} = 6 \][/tex]

7. Square both sides to solve for [tex]\( x \)[/tex]:
[tex]\[ x = 6^2 \][/tex]
[tex]\[ x = 36 \][/tex]

So, the value of [tex]\( x \)[/tex] is [tex]\( 36 \)[/tex]. Therefore, the correct answer is:
[tex]\[ \boxed{6^2} \][/tex]