Find the Domain of 3/√(x-2): Square Root Function Analysis

Domain Analysis with Square Root Restrictions

Look at the following function:

3x2 \frac{3}{\sqrt{x-2}}

What is the domain of the function?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Does the function have a domain? If so, what is it?
00:04 A root must be for a positive number greater than 0
00:10 Let's isolate X
00:16 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Look at the following function:

3x2 \frac{3}{\sqrt{x-2}}

What is the domain of the function?

2

Step-by-step solution

To determine the domain of the function 3x2 \frac{3}{\sqrt{x-2}} , we need to consider the constraints imposed by the square root and the fraction.

First, the expression inside the square root must be non-negative: x20 x - 2 \geq 0 . This simplifies to:

  • x2 x \geq 2

However, because the expression x2 \sqrt{x-2} is in the denominator of the fraction, we must also ensure that it is not equal to zero, as division by zero is undefined. Therefore, we have:

  • x20 x - 2 \neq 0

Solving this inequality gives:

  • x2 x \neq 2

Together, the solution to both conditions is that x x must be greater than 2 to ensure the function is defined. Thus, the domain of the function is:

x>2 x > 2

Therefore, the correct choice for the domain is x>2 x > 2 .

3

Final Answer

x>2 x > 2

Key Points to Remember

Essential concepts to master this topic
  • Square Root Rule: Expression under radical must be non-negative
  • Denominator Restriction: x20 \sqrt{x-2} \neq 0 means x-2 > 0
  • Check Domain: Test x=3: 332=31=3 \frac{3}{\sqrt{3-2}} = \frac{3}{1} = 3

Common Mistakes

Avoid these frequent errors
  • Using x ≥ 2 instead of x > 2
    Don't forget the denominator cannot equal zero! Using x ≥ 2 allows x = 2, which makes x2=0 \sqrt{x-2} = 0 and creates division by zero. Always exclude values that make denominators zero.

Practice Quiz

Test your knowledge with interactive questions

\( 22(\frac{2}{x}-1)=30 \)

What is the domain of the equation above?

FAQ

Everything you need to know about this question

Why can't x equal 2 if the square root of 0 exists?

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Great question! While 0=0 \sqrt{0} = 0 is perfectly valid, having zero in the denominator makes the fraction undefined. Think of it like asking "what's 3 ÷ 0?" - it has no answer!

What's the difference between x ≥ 2 and x > 2?

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The symbol ≥ means "greater than or equal to" while > means "strictly greater than." Since x = 2 makes our denominator zero, we must exclude x = 2, so we use the strict inequality x > 2.

How do I find what makes the square root undefined?

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Set the expression under the square root less than zero. For x2 \sqrt{x-2} , solve x - 2 < 0 to get x < 2. These are the values that make the square root undefined.

Do I need to check both the square root AND the fraction?

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Yes! First check that x - 2 ≥ 0 for the square root to exist. Then check that the denominator ≠ 0. Combine both conditions to get your final domain.

Can the domain ever be empty for this type of function?

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It's possible! If the conditions conflict (like needing x > 5 AND x < 3 at the same time), then no values of x work and the domain would be empty. But that's not the case here.

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