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Which statement describes the solutions of this equation?
[tex]\frac{x}{3}+\frac{x-1}{x+4}=\frac{x+3}{x+4}[/tex]

A. The equation has no valid solutions and two extraneous solutions.
B. The equation has one valid solution and no extraneous solutions.
C. The equation has one valid solution and one extraneous solution.
D. The equation has two valid solutions and no extraneous solutions.


Sagot :

To determine which statement best describes the solutions to the given equation:
[tex]\[ \frac{x}{3} + \frac{x-1}{x+4} = \frac{x+3}{x+4} \][/tex]
Let's go through solving the equation step-by-step.

1. Combine the Fractions on the Right Side:
We observe that the denominators [tex]\((x + 4)\)[/tex] are the same for the second term on the left and the term on the right. We can simplify:
[tex]\[ \frac{x}{3} + \frac{(x-1) - (x+3)}{x+4} = 0 \][/tex]
Simplifying the numerator inside the second fraction:
[tex]\[ \frac{x}{3} + \frac{x-1 - x-3}{x+4} = \frac{x}{3} - \frac{4}{x+4} \][/tex]

2. Set the Entire Expression to Zero:
Now, set the combined fractions to zero:
[tex]\[ \frac{x}{3} - \frac{4}{x+4} = 0 \][/tex]

3. Eliminate the Fractions:
To clear the fractions, multiply through by a common denominator, which would be [tex]\(3(x+4)\)[/tex]:
[tex]\[ x(x+4) - 4 \cdot 3 = 0 \][/tex]
This simplifies to:
[tex]\[ x^2 + 4x - 12 = 0 \][/tex]

4. Solve the Quadratic Equation:
Use the quadratic formula [tex]\(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\)[/tex] where [tex]\(a = 1\)[/tex], [tex]\(b = 4\)[/tex], and [tex]\(c = -12\)[/tex]:
[tex]\[ x = \frac{-4 \pm \sqrt{16 + 48}}{2} = \frac{-4 \pm \sqrt{64}}{2} = \frac{-4 \pm 8}{2} \][/tex]
This gives two solutions:
[tex]\[ x = \frac{4}{2} = 2 \quad \text{and}\quad x = \frac{-12}{2} = -6 \][/tex]

5. Check for Extraneous Solutions:
Substitute [tex]\(x = -6\)[/tex] and [tex]\(x = 2\)[/tex] into the original equation to validate if they are solutions:

- For [tex]\(x = 2\)[/tex]:
[tex]\[ \frac{2}{3} + \frac{1}{6} = \frac{5}{6} \quad \text{which simplifies correctly to}\quad \frac{5}{6} = \frac{5}{6} \][/tex]
[tex]\(x = 2\)[/tex] is a valid solution.

- For [tex]\(x = -6\)[/tex]:
[tex]\[ \frac{-6}{3} + \frac{-7}{-2} = -2 + \frac{7}{-2} \quad \text{denominator cannot be zero} \][/tex]
As [tex]\(x = -6\)[/tex] results in an invalid denominator in the given equation.

6. Conclude the Number of Solutions:
Since [tex]\(x = 2\)[/tex] is a valid solution and [tex]\(x = -6\)[/tex] is an extraneous solution:

The correct statement is:
D. The equation has two valid solutions and no extraneous solutions.

With this detailed explanation, we conclude that the solution accurately corresponds to:
D. The equation has two valid solutions and no extraneous solutions.