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Simplify the expression given below.

[tex]\[ \frac{1}{2x^2 - 4x} - \frac{2}{x} \][/tex]

A. [tex]\[ \frac{-1}{2x(x-2)} \][/tex]

B. [tex]\[ \frac{4x - 7}{2x(x-2)} \][/tex]

C. [tex]\[ \frac{-3x - 8}{2x(x-2)} \][/tex]

D. [tex]\[ \frac{-4x + 9}{2x(x-2)} \][/tex]


Sagot :

To simplify the given expression [tex]\(\frac{1}{2 x^2-4 x}-\frac{2}{x}\)[/tex], let's follow these steps:

### Step 1: Factor the Denominator of the First Term
The first term is [tex]\(\frac{1}{2 x^2-4 x}\)[/tex]. We can factor the denominator as follows:
[tex]\[ 2 x^2 - 4 x = 2x(x-2) \][/tex]
So, the expression becomes:
[tex]\[ \frac{1}{2x(x-2)} \][/tex]

### Step 2: Rewriting the Original Expression
The original expression is now:
[tex]\[ \frac{1}{2x(x-2)} - \frac{2}{x} \][/tex]

### Step 3: Finding a Common Denominator
The common denominator for the two terms is [tex]\(2x(x-2)\)[/tex]. So, we rewrite each fraction with this common denominator.

For the term [tex]\(\frac{2}{x}\)[/tex], we need to multiply the numerator and the denominator by [tex]\(2(x-2)\)[/tex]:
[tex]\[ \frac{2}{x} = \frac{2 \cdot 2(x-2)}{x \cdot 2(x-2)} = \frac{4(x-2)}{2x(x-2)} \][/tex]

### Step 4: Combining the Fractions
Combine the fractions over the common denominator [tex]\(2x(x-2)\)[/tex]:
[tex]\[ \frac{1}{2x(x-2)} - \frac{4(x-2)}{2x(x-2)} = \frac{1 - 4(x-2)}{2x(x-2)} \][/tex]

### Step 5: Simplify the Numerator
Now simplify the numerator:
[tex]\[ 1 - 4(x-2) = 1 - 4x + 8 = 9 - 4x \][/tex]

### Step 6: Writing the Final Expression
Combining these results, we get:
[tex]\[ \frac{1 - 4(x-2)}{2x(x-2)} = \frac{9 - 4x}{2x(x-2)} \][/tex]

So the simplified expression is:
[tex]\[ \frac{9 - 4x}{2x(x-2)} \][/tex]

### Conclusion
Therefore, the answer is:
[tex]\[ \boxed{\frac{9 - 4x}{2x(x-2)}} \][/tex]

Now, let's match this with one of the given options. We see that option D is [tex]\(\frac{9 - 4x}{2 x(x-2)}\)[/tex], which matches our simplified expression. Hence, the answer is D.