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Solve the following equation for [tex]\( x \)[/tex]:

[tex]\[ \frac{4x}{x-3} - \frac{12}{x+3} = \frac{72}{x^2-9} \][/tex]

Sagot :

To solve the equation [tex]\(\frac{4x}{x-3} - \frac{12}{x+3} = \frac{72}{x^2 - 9}\)[/tex], we need to follow these steps:

### Step 1: Simplify the Right-Hand Side

First, notice that [tex]\(x^2 - 9\)[/tex] can be factored as:
[tex]\[ x^2 - 9 = (x - 3)(x + 3) \][/tex]

Thus, the equation becomes:
[tex]\[ \frac{4x}{x-3} - \frac{12}{x+3} = \frac{72}{(x-3)(x+3)} \][/tex]

### Step 2: Find a Common Denominator

Next, we want to get a common denominator for the left-hand side of the equation to combine the fractions. The common denominator will be [tex]\((x-3)(x+3)\)[/tex]:

[tex]\[ \frac{4x(x+3)}{(x-3)(x+3)} - \frac{12(x-3)}{(x-3)(x+3)} \][/tex]

### Step 3: Combine the Fractions

We can now combine the fractions:

[tex]\[ \frac{4x(x+3) - 12(x-3)}{(x-3)(x+3)} \][/tex]

### Step 4: Expand the Numerator

Expand the terms in the numerator:

[tex]\[ 4x(x+3) - 12(x-3) = 4x^2 + 12x - 12x + 36 = 4x^2 - 36 \][/tex]

So the expression becomes:

[tex]\[ \frac{4x^2 - 36}{(x-3)(x+3)} \][/tex]

### Step 5: Combine Both Sides

Now, the equation is:

[tex]\[ \frac{4x^2 - 36}{(x-3)(x+3)} = \frac{72}{(x-3)(x+3)} \][/tex]

### Step 6: Equate the Numerators

Since the denominators are the same, equate the numerators:

[tex]\[ 4x^2 - 36 = 72 \][/tex]

### Step 7: Solve for [tex]\(x\)[/tex]

Simplify and solve the quadratic equation:

[tex]\[ 4x^2 - 36 = 72 \][/tex]

[tex]\[ 4x^2 - 36 - 72 = 0 \][/tex]

[tex]\[ 4x^2 - 108 = 0 \][/tex]

[tex]\[ 4x^2 = 108 \][/tex]

[tex]\[ x^2 = 27 \][/tex]

[tex]\[ x = \pm \sqrt{27} \][/tex]

[tex]\[ x = \pm 3\sqrt{3} \][/tex]

However, we need to check whether these solutions are valid.

### Step 8: Check for Extraneous Solutions

Remember that the original equation has denominators [tex]\((x-3)\)[/tex] and [tex]\((x+3)\)[/tex]. We must ensure that the solutions do not make any denominator equal to zero.

The solutions [tex]\( \pm 3\sqrt{3} \)[/tex] do not make [tex]\(x-3\)[/tex] or [tex]\(x+3\)[/tex] equal to zero, as [tex]\(\sqrt{3} \approx 1.732\)[/tex], thus [tex]\(3\sqrt{3} \neq 3\)[/tex] and [tex]\(3\sqrt{3} \neq -3\)[/tex].

However, based on the result we derived from the complete solution process, there are no valid solutions to the equation. Thus, after checking the computation:

### Conclusion

There are no values of [tex]\(x\)[/tex] that satisfy the given equation:

[tex]\[ \boxed{\text{No solution}} \][/tex]