If $\frac{2}{2 + \frac{2}{2 + \frac{2}{x}}} = 3$, then $x$ is equal to
Aptitude
Simplification
Difficulty: Hard
Choose an option
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A-\frac{4}{7}
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B\frac{4}{7}
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C-\frac{7}{4}
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D\frac{7}{4}
Answer
Correct Answer: -\frac{4}{7}
Explanation
### Concept & Strategy
Unlike standard continued fraction problems where you simplify from the bottom up, this is an **Inverse Continued Fraction Equation**. Because the unknown $x$ is buried at the very bottom, but the total value of the expression is known (it equals 3), the fastest strategy is to solve from the **top down**.
### Step-by-Step Solution
We will isolate the terms layer by layer, starting from the outermost shell.
* **Step 1: Isolate the main denominator**
The equation is $\frac{2}{\text{Denominator}} = 3$.
Rearranging this gives:
$$\text{Denominator} = \frac{2}{3}$$
So, $2 + \frac{2}{2 + \frac{2}{x}} = \frac{2}{3}$
* **Step 2: Isolate the next nested fraction**
Subtract 2 from both sides:
$$\frac{2}{2 + \frac{2}{x}} = \frac{2}{3} - 2$$
$$\frac{2}{2 + \frac{2}{x}} = \frac{2 - 6}{3} = -\frac{4}{3}$$
* **Step 3: Isolate the next denominator**
We have $\frac{2}{\text{Denominator}} = -\frac{4}{3}$.
Rearranging gives $\text{Denominator} = 2 \times \left(-\frac{3}{4}\right) = -\frac{6}{4} = -\frac{3}{2}$.
So, $2 + \frac{2}{x} = -\frac{3}{2}$
* **Step 4: Solve for $x$**
Subtract 2 from both sides:
$$\frac{2}{x} = -\frac{3}{2} - 2$$
$$\frac{2}{x} = \frac{-3 - 4}{2} = -\frac{7}{2}$$
Invert both sides and multiply to find $x$:
$$\frac{x}{2} = -\frac{2}{7}$$
$$x = 2 \times \left(-\frac{2}{7}\right) = -\frac{4}{7}$$
### Exam Strategy & Shortcut
The top-down approach *is* the shortcut. If you try to simplify this from the bottom up (by finding a common denominator for $2 + 2/x$, then inverting, then adding 2, etc.), you will create massive, algebraically heavy expressions that are incredibly prone to silly mistakes. Working backwards with simple integers is always faster.
### Common Pitfall
The biggest danger here is losing track of negative signs. In Step 2, subtracting 2 from $2/3$ yields a negative number ($-4/3$). If you accidentally write positive $4/3$, you will end up with an incorrect positive fraction for $x$. Always double-check your sign arithmetic when moving terms across the equals sign.
### Final Answer
Therefore, the correct answer is **-\frac{4}{7}**.