# Lesson 22

Solving Rational Equations

### Problem 1

Identify all values of $$x$$ that make the equation true.

1. $$\frac{2x+1}{x}=\frac{1}{x-2}$$
2. $$\frac{1}{x+2}=\frac{2}{x-1}$$
3. $$\frac{x+3}{1-x} = \frac{x+1}{x+2}$$
4. $$\frac{x+2}{x+8}= \frac{1}{x+2}$$

### Problem 2

Kiran is solving $$\frac{2x-3}{x-1} = \frac{2}{x(x-1)}$$ for $$x$$, and he uses these steps:

\begin{align} \frac{2x-3}{x-1} &= \frac{2}{x(x-1)}\\ (x-1)\left(\frac{2x-3}{x-1} \right) &= x(x-1) \left( \frac{2}{x(x-1)} \right)\\ 2x-3 &= 2\\ 2x &= 5 \\ x &= 2.5 \\ \end{align}

He checks his answer and finds that it isn't a solution to the original equation, so he writes “no solutions.” Unfortunately, Kiran made a mistake while solving. Find his error and calculate the actual solution(s).

### Problem 3

Identify all values of $$x$$ that make the equation true.

1. $$x=\frac{25}{x}$$
2. $$x+2= \frac{6x-3}{x}$$
3. $$\frac{x}{x^2} = \frac{3}{x}$$
4. $$\frac{6x^2+18x}{2x^3} = \frac{5}{x}$$

### Problem 4

Is this the graph of $$g(x)=\text-x^4(x+3)$$ or $$h(x)=x^4(x+3)$$? Explain how you know.

### Solution

(From Unit 2, Lesson 10.)

### Problem 5

Rewrite the rational function $$g(x) = \frac{x-9}{x}$$ in the form $$g(x) = c + \frac{r}{x}$$, where $$c$$ and $$r$$ are constants.

### Solution

Elena has a boat that would go 9 miles per hour in still water. She travels downstream for a certain distance and then back upstream to where she started. Elena notices that it takes her 4 hours to travel upstream and 2 hours to travel downstream. The river’s speed is $$r$$ miles per hour. Write an expression that will help her solve for $$r$$.