Math Problem Statement

solve for x, stating restrictions: - x/(x+1) - 5/(x+4) = 1/6

Solution

We are given the equation:

xx+15x+4=16- \frac{x}{x+1} - \frac{5}{x+4} = \frac{1}{6}

Step 1: Identify restrictions

The denominators x+1x+1 and x+4x+4 cannot be zero, because division by zero is undefined. Therefore, the restrictions on xx are: x+10andx+40x + 1 \neq 0 \quad \text{and} \quad x + 4 \neq 0 x1andx4x \neq -1 \quad \text{and} \quad x \neq -4 Thus, xx cannot be 1-1 or 4-4.

Step 2: Eliminate fractions by finding the common denominator

The least common denominator (LCD) of x+1x+1, x+4x+4, and 6 is 6(x+1)(x+4)6(x+1)(x+4). Multiply both sides of the equation by this LCD to eliminate the denominators:

6(x+1)(x+4)(xx+15x+4)=6(x+1)(x+4)166(x+1)(x+4) \left( - \frac{x}{x+1} - \frac{5}{x+4} \right) = 6(x+1)(x+4) \cdot \frac{1}{6}

Step 3: Simplify each term

On the left-hand side:

  • The first term simplifies to x6(x+4)-x \cdot 6(x+4), since the x+1x+1 cancels out.
  • The second term simplifies to 56(x+1)-5 \cdot 6(x+1), since the x+4x+4 cancels out.

The right-hand side simplifies to (x+1)(x+4)(x+1)(x+4).

So, we now have the equation:

6x(x+4)30(x+1)=(x+1)(x+4)-6x(x+4) - 30(x+1) = (x+1)(x+4)

Step 4: Expand both sides

Expand both sides of the equation:

6x(x+4)=6x224x-6x(x+4) = -6x^2 - 24x 30(x+1)=30x30-30(x+1) = -30x - 30 (x+1)(x+4)=x2+5x+4(x+1)(x+4) = x^2 + 5x + 4

Substitute these expressions back into the equation:

6x224x30x30=x2+5x+4-6x^2 - 24x - 30x - 30 = x^2 + 5x + 4

Combine like terms on the left-hand side:

6x254x30=x2+5x+4-6x^2 - 54x - 30 = x^2 + 5x + 4

Step 5: Move all terms to one side of the equation

Move all terms to the left-hand side:

6x254x30x25x4=0-6x^2 - 54x - 30 - x^2 - 5x - 4 = 0 7x259x34=0-7x^2 - 59x - 34 = 0

Step 6: Solve the quadratic equation

We now have the quadratic equation:

7x259x34=0-7x^2 - 59x - 34 = 0

Use the quadratic formula to solve for xx:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Where a=7a = -7, b=59b = -59, and c=34c = -34.

Step 7: Apply the quadratic formula

First, calculate the discriminant:

b24ac=(59)24(7)(34)=3481952=2529b^2 - 4ac = (-59)^2 - 4(-7)(-34) = 3481 - 952 = 2529

Now, apply the quadratic formula:

x=(59)±25292(7)=59±252914x = \frac{-(-59) \pm \sqrt{2529}}{2(-7)} = \frac{59 \pm \sqrt{2529}}{-14}

Approximating 2529\sqrt{2529}:

252950.29\sqrt{2529} \approx 50.29

Thus:

x=59±50.2914x = \frac{59 \pm 50.29}{-14}

Step 8: Find the two solutions

Now compute the two possible values for xx:

  1. x1=5950.2914=8.71140.62x_1 = \frac{59 - 50.29}{-14} = \frac{8.71}{-14} \approx -0.62
  2. x2=59+50.2914=109.29147.81x_2 = \frac{59 + 50.29}{-14} = \frac{109.29}{-14} \approx -7.81

Step 9: Check for restrictions

Since neither 0.62-0.62 nor 7.81-7.81 equals 1-1 or 4-4, these values are valid solutions.

Final answer:

The solutions are: x0.62andx7.81x \approx -0.62 \quad \text{and} \quad x \approx -7.81 The restrictions are x1x \neq -1 and x4x \neq -4.


Would you like more details on any part of this process or further clarifications?

Here are 5 related questions:

  1. How does the quadratic formula work in solving equations?
  2. What is the significance of the discriminant in the quadratic formula?
  3. Can you explain how to find the least common denominator for complex fractions?
  4. How do restrictions in rational equations impact solutions?
  5. Why do we need to check for excluded values after solving a rational equation?

Tip: Always check for restrictions when solving rational equations to avoid dividing by zero.

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Equations
Quadratic Equations

Formulas

Quadratic formula: x = (-b ± √(b² - 4ac)) / 2a
Least Common Denominator (LCD)

Theorems

Quadratic Formula
Restrictions in Rational Equations

Suitable Grade Level

Grades 9-12