Chapter 9: Problem 13
Solve each proportion. \(\frac{x}{3}=\frac{12}{18}\)
Short Answer
Expert verified
The value of \( x \) is 2.
Step by step solution
01
Cross-Multiply
Proportions can be solved using the cross-multiplication method. Here, multiply both sides of the equation's numerator by the opposite side's denominator. Thus, multiply 18 by \( x \) and 3 by 12. This gives the equation:\[ 18x = 3 imes 12 \]
02
Simplify Right Side
Calculate the product on the right-hand side of the equation: \( 3 imes 12 = 36 \). This updates our equation to:\[ 18x = 36 \]
03
Solve for x
To isolate \( x \), divide both sides of the equation by 18, which is the coefficient of \( x \):\[ x = \frac{36}{18} \]
04
Simplify the Fraction
Simplify the fraction \( \frac{36}{18} \). Since 36 divided by 18 equals 2, we find:\[ x = 2 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cross-Multiplication
Cross-multiplication is an essential technique for solving equations involving proportions. A proportion is simply two ratios that are considered equal, much like in the exercise with \( \frac{x}{3} = \frac{12}{18} \). This technique shines because it helps eliminate fractions, which are often perceived as complex.When you cross-multiply, you simply multiply each numerator by the opposite denominator. This concept is akin to creating a balance by crossing across the equal sign. For instance:
- Multiply 18 and \( x \) from the first ratio, and 3 and 12 from the second, resulting in the equation: \( 18x = 3 \times 12 \).
- This step converts a single equation with fractions into an equation without fractions: \( 18x = 36 \).
Solving Equations
Once you have cross-multiplied, you're often left with an algebraic equation that needs solving, just like in our example: \( 18x = 36 \). Solving equations typically involves finding the value of the unknown, represented by a variable like \( x \), that makes the equation true.The goal is to isolate \( x \) on one side of the equation. Here's what you do:
- Since \( 18x = 36 \), to solve for \( x \), divide both sides by 18, the coefficient of \( x \).
- This division simplifies the equation to \( x = \frac{36}{18} \).
Simplifying Fractions
Fractions can often appear daunting, but simplifying them can make mathematics much more approachable. In the exercise, after solving the equation, you get \( x = \frac{36}{18} \). Now, it's time to simplify this fraction to its lowest terms.When simplifying fractions:
- Find the greatest common divisor (GCD) of the numerator and the denominator. In this case, the GCD of 36 and 18 is 18.
- Divide both the numerator and the denominator by this GCD. So, divide 36 by 18 and 18 by 18.
- This calculation yields \( \frac{36}{18} = 2 \).