Solve the Fraction Equation: When 1/2 × ? = 1/4

Fraction Division with Reciprocal Method

12×?=14 \frac{1}{2}\times?=\frac{1}{4}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the unknown
00:03 Isolate the unknown
00:06 Write division as multiplication by the reciprocal
00:09 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

12×?=14 \frac{1}{2}\times?=\frac{1}{4}

2

Step-by-step solution

To solve the equation 12×?=14 \frac{1}{2} \times ? = \frac{1}{4} , we need to find the number that makes this equation true.

Let's perform the operations step-by-step:

  • Step 1: Start with the given equation: 12×x=14 \frac{1}{2} \times x = \frac{1}{4} .
  • Step 2: To isolate x x , divide both sides by 12 \frac{1}{2} . This gives us: x=14÷12 x = \frac{1}{4} \div \frac{1}{2} .
  • Step 3: Dividing by a fraction is the same as multiplying by its reciprocal. Thus, we have: x=14×21 x = \frac{1}{4} \times \frac{2}{1} .
  • Step 4: Multiply the fractions: x=1×24×1=24 x = \frac{1 \times 2}{4 \times 1} = \frac{2}{4} .
  • Step 5: Simplify the fraction: x=12 x = \frac{1}{2} .

Therefore, the missing number is 12\frac{1}{2}. This matches choice 4 from the given options.

3

Final Answer

12 \frac{1}{2}

Key Points to Remember

Essential concepts to master this topic
  • Rule: Division by a fraction equals multiplication by its reciprocal
  • Technique: 14÷12=14×21=24 \frac{1}{4} \div \frac{1}{2} = \frac{1}{4} \times \frac{2}{1} = \frac{2}{4}
  • Check: Substitute back: 12×12=14 \frac{1}{2} \times \frac{1}{2} = \frac{1}{4}

Common Mistakes

Avoid these frequent errors
  • Multiplying by the denominator instead of dividing by the fraction
    Don't just multiply both sides by 2 to get x = 1/2 directly! This skips the division step and creates confusion about reciprocals. Always divide both sides by the coefficient using the reciprocal method.

Practice Quiz

Test your knowledge with interactive questions

\( \frac{2}{3}\times\frac{5}{7}= \)

FAQ

Everything you need to know about this question

Why do I flip the fraction when dividing?

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Dividing by a fraction is the same as multiplying by its reciprocal! The reciprocal of 12 \frac{1}{2} is 21 \frac{2}{1} . This rule makes division problems much easier to solve.

How do I find the reciprocal of a fraction?

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Simply flip the numerator and denominator! For 12 \frac{1}{2} , the reciprocal is 21 \frac{2}{1} or just 2. For 34 \frac{3}{4} , it would be 43 \frac{4}{3} .

Can I solve this without using reciprocals?

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You could think of it as "what times 1/2 equals 1/4?" but using reciprocals is the standard method that works for all fraction division problems and prepares you for more complex equations.

Why does 1/4 × 2 equal 1/2 instead of 2/4?

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Actually, 14×2=24 \frac{1}{4} \times 2 = \frac{2}{4} , and then we simplify: 24=12 \frac{2}{4} = \frac{1}{2} . Always reduce fractions to their simplest form!

How do I check my answer is correct?

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Substitute your answer back into the original equation! If 12×12=14 \frac{1}{2} \times \frac{1}{2} = \frac{1}{4} , then you know 12 \frac{1}{2} is correct.

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