Solve Complex Fraction Equation: (1/x - 1/2)² = (9/4)(1/x - 1/3)²

Complex Fractions with Substitution Method

(1x12)2(1x13)2=94 \frac{(\frac{1}{x}-\frac{1}{2})^2}{(\frac{1}{x}-\frac{1}{3})^2}=\frac{9}{4}

Find X

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:12 Let's find the value of X.
00:15 First, we'll extract the root.
00:19 Remember, taking a root gives us two choices: positive and nega tive.
00:25 This step helps cancel out the squares.
00:29 We'll extract the root for both the numerator and the denomina tor.
00:36 The second choice is negative.
00:41 Let's solve the positive option first.
00:46 We'll multiply by the reciprocal to get rid of the fractions.
00:54 Open the parentheses carefully and multiply by each term.
01:03 Now, isolate X.
01:07 Collect all the terms together.
01:13 This option doesn't work because division by zero isn't allo wed.
01:18 Let's try the negative option now.
01:22 Again, multiply by the reciprocal to eliminate fractions.
01:28 Remember to open the parentheses and multiply by each factor.
01:35 Isolate X in this option.
01:54 And that's how we solve this problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

(1x12)2(1x13)2=94 \frac{(\frac{1}{x}-\frac{1}{2})^2}{(\frac{1}{x}-\frac{1}{3})^2}=\frac{9}{4}

Find X

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Expand and simplify the numerator (1x12)2 (\frac{1}{x} - \frac{1}{2})^2 .
  • Step 2: Expand and simplify the denominator (1x13)2 (\frac{1}{x} - \frac{1}{3})^2 .
  • Step 3: Set up the equation as a proportion and solve for x x .

Let’s work through each step:
Step 1: Using the formula for the square of a difference, expand the numerator:

(1x12)2=(1x)22(1x)(12)+(12)2=1x21x+14(\frac{1}{x} - \frac{1}{2})^2 = \left(\frac{1}{x}\right)^2 - 2\left(\frac{1}{x}\right)\left(\frac{1}{2}\right) + \left(\frac{1}{2}\right)^2 = \frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}.

Step 2: Similarly, expand the denominator:

(1x13)2=(1x)22(1x)(13)+(13)2=1x223x+19(\frac{1}{x} - \frac{1}{3})^2 = \left(\frac{1}{x}\right)^2 - 2\left(\frac{1}{x}\right)\left(\frac{1}{3}\right) + \left(\frac{1}{3}\right)^2 = \frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}.

Step 3: Substitute these into the original equation and solve the proportion:

1x21x+141x223x+19=94\frac{\frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}}{\frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}} = \frac{9}{4}.

Cross-multiply to clear the fractions:

4(1x21x+14)=9(1x223x+19)4\left(\frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}\right) = 9\left(\frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}\right).

Simplifying both sides gives:

4(1x21x+14)=41x241x+14(\frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}) = 4\frac{1}{x^2} - 4\frac{1}{x} + 1.

9(1x223x+19)=91x261x+19(\frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}) = 9\frac{1}{x^2} - 6\frac{1}{x} + 1.

Equating the expressions, we have:

41x241x+1=91x261x+14\frac{1}{x^2} - 4\frac{1}{x} + 1 = 9\frac{1}{x^2} - 6\frac{1}{x} + 1.

Subtract 1 from both sides and collect like terms:

41x+1=51x221x-4\frac{1}{x} + 1 = 5\frac{1}{x^2} - 2\frac{1}{x}.

21x51x2=0-2\frac{1}{x} - 5\frac{1}{x^2} = 0.

Factoring gives:

51x(x2)=05\frac{1}{x}(x - 2) = 0.

Therefore, the solution for x x should satisfy x2=0 x - 2 = 0 , so x=2.5 x = 2.5 .

Thus, the value of x x is 2.5\boxed{2.5}.

3

Final Answer

2.5

Key Points to Remember

Essential concepts to master this topic
  • Substitution: Let u=1x u = \frac{1}{x} to simplify complex fraction equations
  • Square Roots: When solving (ua)2(ub)2=k \frac{(u-a)^2}{(u-b)^2} = k , take square root of both sides first
  • Check: Substitute x=2.5 x = 2.5 back: both sides equal 94 \frac{9}{4}

Common Mistakes

Avoid these frequent errors
  • Expanding the squared terms instead of taking square roots first
    Don't expand (1x12)2 (\frac{1}{x} - \frac{1}{2})^2 and (1x13)2 (\frac{1}{x} - \frac{1}{3})^2 immediately = messy algebra with 1x2 \frac{1}{x^2} terms! This creates unnecessary complexity and calculation errors. Always take the square root of both sides first: 1x121x13=±32 \frac{\frac{1}{x} - \frac{1}{2}}{\frac{1}{x} - \frac{1}{3}} = \pm\frac{3}{2} .

Practice Quiz

Test your knowledge with interactive questions

\( (4b-3)(4b-3) \)

Rewrite the above expression as an exponential summation expression:

FAQ

Everything you need to know about this question

Why should I use substitution with u=1x u = \frac{1}{x} ?

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Substitution makes the equation look simpler! Instead of working with 1x \frac{1}{x} everywhere, you get (u12)2(u13)2=94 \frac{(u-\frac{1}{2})^2}{(u-\frac{1}{3})^2} = \frac{9}{4} , which is easier to handle.

Should I take the square root of both sides first?

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Yes! Since you have squares on both sides, taking square roots gives you: u12u13=±32 \frac{u-\frac{1}{2}}{u-\frac{1}{3}} = \pm\frac{3}{2} . This avoids messy expansion and is much faster.

Why do I get a ± when taking square roots?

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When you take the square root of both sides of an equation, you must consider both positive and negative possibilities. This gives you two cases to solve, potentially leading to multiple solutions.

How do I solve the linear equation after taking square roots?

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Cross-multiply to clear fractions! For u12u13=32 \frac{u-\frac{1}{2}}{u-\frac{1}{3}} = \frac{3}{2} , you get: 2(u12)=3(u13) 2(u-\frac{1}{2}) = 3(u-\frac{1}{3}) , then solve for u.

What if I get multiple values for u?

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Remember that u=1x u = \frac{1}{x} , so you need to find x=1u x = \frac{1}{u} for each valid u-value. Check that your x-values don't make any denominator zero!

How do I verify my answer is correct?

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Substitute x=2.5 x = 2.5 into the original equation. Calculate 1x=0.4 \frac{1}{x} = 0.4 , then check that both sides equal 94=2.25 \frac{9}{4} = 2.25 .

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