Rational Equations
1. Stating the problems:
- Problem 1: Solve the equation $$\frac{1}{x} + \frac{1}{x+1} = \frac{1}{x(x+1)}$$.
- Problem 2: Solve the equation $$\frac{1}{x+2} - \frac{4}{x-2} = \frac{2x}{x^2 - 4}$$.
- Problem 3: Solve the equation $$2\left(\frac{x}{x-3}\right)^2 + \frac{5x}{3-x} + 3 = 0$$.
2. Problem 1 solution:
- The denominators are $x$, $x+1$, and $x(x+1)$.
- Multiply both sides by $x(x+1)$ to clear denominators:
$$x(x+1)\left(\frac{1}{x} + \frac{1}{x+1}\right) = x(x+1) \cdot \frac{1}{x(x+1)}$$
- Simplify left side:
$$ (x+1) + x = 1$$
- Combine like terms:
$$2x + 1 = 1$$
- Subtract 1 from both sides:
$$2x = 0$$
- Divide both sides by 2:
$$x = 0$$
- Check for restrictions: denominators cannot be zero, so $x \neq 0$ and $x \neq -1$.
- Since $x=0$ is restricted, no solution for problem 1.
3. Problem 2 solution:
- Note that $x^2 - 4 = (x-2)(x+2)$.
- Multiply both sides by $x^2 - 4$:
$$ (x^2 - 4) \left( \frac{1}{x+2} - \frac{4}{x-2} \right) = (x^2 - 4) \cdot \frac{2x}{x^2 - 4}$$
- Simplify left side:
$$ (x-2) - 4(x+2) = 2x$$
- Expand right side:
$$x - 2 - 4x - 8 = 2x$$
- Combine like terms on left:
$$-3x - 10 = 2x$$
- Add $3x$ to both sides:
$$-10 = 5x$$
- Divide by 5:
$$x = -2$$
- Restrictions: denominators require $x \neq -2$ and $x \neq 2$.
- $x = -2$ is excluded, so no solution for problem 2.
4. Problem 3 solution:
- Note $3 - x = -(x - 3)$ so $$\frac{5x}{3-x} = \frac{5x}{-(x-3)} = -\frac{5x}{x-3}$$.
- Rewrite equation:
$$2\left(\frac{x}{x-3}\right)^2 - \frac{5x}{x-3} + 3 = 0$$
- Let $$y = \frac{x}{x-3}$$, so equation becomes:
$$2y^2 - 5y + 3 = 0$$
- Solve quadratic in $y$ using quadratic formula:
$$y = \frac{5 \pm \sqrt{(-5)^2 - 4 \cdot 2 \cdot 3}}{2 \cdot 2} = \frac{5 \pm \sqrt{25 - 24}}{4} = \frac{5 \pm 1}{4}$$
- Two solutions for $y$:
$$y_1 = \frac{5 + 1}{4} = \frac{6}{4} = \frac{3}{2}$$
$$y_2 = \frac{5 - 1}{4} = \frac{4}{4} = 1$$
- Recall $$y = \frac{x}{x-3}$$, so solve:
For $y_1 = \frac{3}{2}$:
$$\frac{x}{x-3} = \frac{3}{2} \Rightarrow 2x = 3(x - 3) \Rightarrow 2x = 3x - 9 \Rightarrow -x = -9 \Rightarrow x = 9$$
For $y_2 = 1$:
$$\frac{x}{x-3} = 1 \Rightarrow x = x - 3$$
No solution from second equation.
- Restrictions: denominator $x - 3 \neq 0 \Rightarrow x \neq 3$.
- Final solution is $x=9$.
Final answers:
- Problem 1: No valid solution.
- Problem 2: No valid solution.
- Problem 3: $x=9$.