Solve for the Denominator in (4x-2)/? = 2: Fraction Equation Practice

Solving Fractions with Unknown Denominators

Complete the corresponding expression for the denominator

4x2?=2 \frac{4x-2}{?}=2

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Complete the appropriate denominator
00:04 We want to isolate the denominator, so we'll multiply by the denominator
00:14 Let's isolate the denominator
00:27 Let's break down the fraction into 2 fractions
00:33 Let's calculate the quotients
00:38 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

Complete the corresponding expression for the denominator

4x2?=2 \frac{4x-2}{?}=2

2

Step-by-step solution

Let's examine the problem, first we'll write the expression on the right side as a fraction (using the fact that dividing a number by 1 does not change its value):

4x2?=24x2?=21 \frac{4x-2}{?}=2 \\ \downarrow\\ \frac{4x-2}{?}=\frac{2}{1}

Now let's think logically, and remember the fraction reduction operation,

In order for the fraction on the left side to be reducible, we want all terms in its numerator to have a common factor. Hence first we'll check if it can be factored, and we'll identify that it indeed can be factored, by using finding a common factor:

4x2?=212(2x1)?=21 \frac{4x-2}{?}=\frac{2}{1} \\ \frac{2(2x-1)}{?}=\frac{2}{1}

Now let's examine the expression on the left side once again:

Note that to obtain the number 2 in the fraction's numerator after reduction, we only need to reduce the algebraic expression (binomial):

2x1 2x-1

Let's verify that with this choice we indeed obtain the expression on the right side:

2(2x1)?=212(2x1)2x1=?2121=!21 \frac{2(2x-1)}{?}=\frac{2}{1} \\ \downarrow\\ \frac{2(2x-1)}{\textcolor{red}{2x-1}}\stackrel{?}{= }\frac{2}{1} \\ \downarrow\\ \boxed{\frac{2}{1}\stackrel{!}{= }\frac{2}{1} }

Therefore this choice is correct.

In other words - the correct answer is answer A.

3

Final Answer

2x1 2x-1

Key Points to Remember

Essential concepts to master this topic
  • Rule: Factor the numerator to find common terms for cancellation
  • Technique: Factor 4x-2 = 2(2x-1), so denominator must be 2x-1
  • Check: Verify that 2(2x1)2x1=2 \frac{2(2x-1)}{2x-1} = 2 by canceling ✓

Common Mistakes

Avoid these frequent errors
  • Not factoring the numerator before solving
    Don't just guess denominators without analyzing the numerator structure = random wrong answers! Students often miss that 4x-2 has a common factor of 2. Always factor the numerator first to identify what must cancel out.

Practice Quiz

Test your knowledge with interactive questions

Determine if the simplification shown below is correct:

\( \frac{7}{7\cdot8}=8 \)

FAQ

Everything you need to know about this question

How do I know what the denominator should be?

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Look at the numerator first! Factor it completely, then think: what would I need to cancel to get the answer on the right side? In 4x2?=2 \frac{4x-2}{?} = 2 , factor to get 2(2x1)? \frac{2(2x-1)}{?} , so you need 2x-1 in the denominator.

Why can't the denominator be x-2?

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Test it! If denominator is x-2, then 4x2x2 \frac{4x-2}{x-2} doesn't simplify to 2 for all values of x. Only 2x-1 works because it creates a factor that cancels perfectly.

What if I can't factor the numerator?

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Not all numerators can be factored easily! But in this case, 4x-2 clearly has a common factor of 2. Look for greatest common factors first - it's usually a number that divides all terms.

How do I verify my answer is correct?

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Substitute your denominator back into the original equation and simplify! 4x22x1=2(2x1)2x1=2 \frac{4x-2}{2x-1} = \frac{2(2x-1)}{2x-1} = 2 ✓ The factors should cancel to give exactly what's on the right side.

Can there be multiple correct denominators?

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No! For any given fraction equation like this, there's only one correct denominator. The algebra determines exactly what it must be - you can't have multiple solutions.

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