Exploring Domains in Rational Fractions: (4/(x-2))×(7x/(x-6))=2

Domain Analysis with Rational Functions

Determine the area of the domain without solving the expression:

(4x2)×(7xx6)=2 (\frac{4}{x-2})\times(\frac{7x}{x-6})=2

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:15 Let's find the domain for substitution.
00:18 Remember, the domain is where we make sure we're not dividing by zero.
00:24 First, we'll isolate X to figure out the domain for substitution.
00:29 Great! That's the first domain. Let's find the second one now.
00:34 Here's the second substitution domain. Combine both, and you've got the full domain.
00:39 And there you have it. That's how we solve this question.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Determine the area of the domain without solving the expression:

(4x2)×(7xx6)=2 (\frac{4}{x-2})\times(\frac{7x}{x-6})=2

2

Step-by-step solution

To solve this problem, we'll determine where the given expression is undefined:

  • Step 1: Identify where the first fraction, 4x2 \frac{4}{x-2} , is undefined. This fraction is undefined when its denominator is zero: x2=0 x-2 = 0 . Thus, x=2 x = 2 .
  • Step 2: Identify where the second fraction, 7xx6 \frac{7x}{x-6} , is undefined. This fraction is undefined when its denominator is zero: x6=0 x-6 = 0 . Thus, x=6 x = 6 .
  • Step 3: The expression is undefined at x=2 x = 2 and x=6 x = 6 .

Therefore, the domain of the expression excludes x=2 x = 2 and x=6 x = 6 .

The correct domain restriction is x2,x6 x \neq 2, x \neq 6 .

3

Final Answer

x2,x6 x≠2,x≠6

Key Points to Remember

Essential concepts to master this topic
  • Domain Rule: Exclude all values making denominators equal zero
  • Technique: Set each denominator to zero: x-2=0 gives x=2
  • Check: Verify exclusions don't make original fractions undefined ✓

Common Mistakes

Avoid these frequent errors
  • Including numerator zeros as domain restrictions
    Don't exclude x=0 just because 7x has x in numerator = wrong domain! Numerators equal zero create zeros, not undefined values. Always exclude only denominator zeros: x=2 and x=6.

Practice Quiz

Test your knowledge with interactive questions

Select the the domain of the following fraction:

\( \frac{6}{x} \)

FAQ

Everything you need to know about this question

Why don't we exclude x=0 even though it's in the numerator?

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When x=0, the numerator 7x becomes zero, making the fraction equal zero (not undefined). Only denominators equal to zero create undefined expressions that must be excluded from the domain.

Do I need to solve the equation to find the domain?

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No! The domain depends only on where the expression is undefined, not on the solutions. Just find where each denominator equals zero and exclude those values.

What if the equation had more fractions?

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The process stays the same! Set each denominator equal to zero, solve for x, and exclude all those values from the domain. Each fraction contributes its own restrictions.

Can the domain change if I simplify the fractions first?

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Be careful! If you cancel common factors, you might accidentally remove domain restrictions. It's safest to find the domain from the original expression before simplifying.

How do I write domain restrictions properly?

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Use the format xa,xb x ≠ a, x ≠ b to list all excluded values, or write as intervals: (,2)(2,6)(6,) (-∞,2) ∪ (2,6) ∪ (6,∞) .

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