Chapter 2: Problem 12
In \(3-20,\) solve each equation and check. $$ \frac{x}{x+5}=\frac{2}{3} $$
Short Answer
Expert verified
The solution is \(x = 10\).
Step by step solution
01
Set the Equation for Cross-Multiplication
We start with the equation \( \frac{x}{x+5} = \frac{2}{3} \). Since we have a proportion, we can use cross-multiplication to solve it. This leads to the equation \( 3x = 2(x+5) \).
02
Distribute the 2 on the Right Side
Distribute the 2 to both terms inside the parentheses on the right side: \( 2(x+5) = 2x + 10 \). Therefore, our equation now is \( 3x = 2x + 10 \).
03
Isolate the Variable x
Subtract \(2x\) from both sides of the equation to get \( 3x - 2x = 10 \). Simplify the left side: \( x = 10 \).
04
Check the Solution
To ensure the solution is correct, substitute \(x = 10\) back into the original equation: \( \frac{10}{10+5} = \frac{2}{3} \). Calculate the left side: \( \frac{10}{15} = \frac{2}{3} \). Simplify \( \frac{10}{15} \) to get \( \frac{2}{3} \), confirming that both sides are equal.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cross-Multiplication
When solving rational equations like \( \frac{x}{x+5} = \frac{2}{3} \), it’s essential to understand cross-multiplication. Rational equations often come in the form of proportions, where two ratios are set equal to each other. Cross-multiplication is the technique that allows us to solve these equations easily.
Here’s how it works for our example:
Here’s how it works for our example:
- Begin with the equation \( \frac{x}{x+5} = \frac{2}{3} \).
- Cross-multiply: Multiply the numerator of each fraction by the denominator of the opposite fraction.
- This results in the equation \(3x = 2(x+5)\), transforming the problem into a linear equation.
Equation Check
Checking your work is a crucial step in solving equations, especially rational ones. It ensures that your solution satisfies the original equation. Here's how to carry out an effective equation check:
- Substitute the found value back into the original equation.
- In our case, substitute \(x = 10\) into \( \frac{x}{x+5} = \frac{2}{3} \).
- This changes the equation to \( \frac{10}{10+5} = \frac{2}{3} \).
- Simplify the left-hand side to get \( \frac{10}{15} = \frac{2}{3} \).
Isolating Variables
After applying cross-multiplication in rational equations, the next critical step is isolating the variable you are solving for. Here’s a straightforward approach:
- Start with the resulting equation from cross-multiplication. For this problem, it’s \(3x = 2x + 10\).
- Isolate \(x\) by getting all terms containing \(x\) on one side. Subtract \(2x\) from both sides to simplify.
- This simplifies to \(3x - 2x = 10\), which further reduces to \(x = 10\).