Chapter 6: Problem 83
Solve formula for the specified variable. \(I=\frac{E}{R+r}\) for \(R\)
Short Answer
Expert verified
R = \(\frac{E - Ir}{I}\)
Step by step solution
01
Understand the Formula
The given formula is: \[ I = \frac{E}{R + r} \]We are to solve this formula for the variable \(R\).
02
Isolate the Denominator
Multiply both sides of the equation by \(R + r\) to get rid of the denominator:\[ I(R + r) = E \]
03
Distribute \(I\)
Distribute \(I\) on the left-hand side:\[ IR + Ir = E \]
04
Isolate the term with \(R\)
Subtract \(Ir\) from both sides of the equation to isolate the term with \(R\):\[ IR = E - Ir \]
05
Solve for \(R\)
Divide both sides of the equation by \(I\) to solve for \(R\):\[ R = \frac{E - Ir}{I} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Algebraic Manipulation
Algebraic manipulation involves reworking an equation to express it in a different form. This can involve a few different processes, but the goal is to transform the given formula while maintaining equality. In our example, we start with the formula:
\( I = \frac{E}{R + r} \)
To solve for the variable \( R \), we apply specific operations such as multiplication, distribution, addition, and subtraction. These steps allow us to rearrange the terms to isolate the target variable.
\( I = \frac{E}{R + r} \)
To solve for the variable \( R \), we apply specific operations such as multiplication, distribution, addition, and subtraction. These steps allow us to rearrange the terms to isolate the target variable.
- Multiplication: We multiply both sides of the formula by \( R + r \) to eliminate the denominator.
- Distribution: We distribute the multiplication over addition inside the parentheses.
- Addition/Subtraction: We rearrange the terms by adding or subtracting quantities to both sides of the equation.
- Division: Finally, we divide to solve for the desired variable.
Isolating Variables
Isolating variables is a key part of solving equations. To isolate a specific variable means to get that variable alone on one side of the equation.
In our example, we want to isolate \( R \) in the equation \( I = \frac{E}{R + r} \).
To achieve isolation:
In our example, we want to isolate \( R \) in the equation \( I = \frac{E}{R + r} \).
To achieve isolation:
- Step 1: Multiply both sides of the equation by \( R + r \) to remove the fraction: \( I(R + r) = E \).
- Step 2: Distribute \( I \) across the terms inside the parentheses: \( IR + Ir = E \).
- Step 3: Remove the term that does not contain the target variable by subtracting \( Ir \) from both sides: \( IR = E - Ir \).
- Step 4: Finally, divide both sides by \( I \) to isolate \( R \): \( R = \frac{E - Ir}{I} \).
Linear Equations
A linear equation is an equation that represents a straight line when plotted on a graph. It usually has the form \( ax + b = c \), where \( a \), \( b \), and \( c \) are constants, and \( x \) is the variable.
In our example, the underlying principle mirrors solving a linear equation, even though the initial formula is in fraction form.
Once we apply algebraic manipulation and isolate the variable, it becomes more straightforward:
In our example, the underlying principle mirrors solving a linear equation, even though the initial formula is in fraction form.
Once we apply algebraic manipulation and isolate the variable, it becomes more straightforward:
- We start with \( I = \frac{E}{R + r} \), a form that can initially seem complex due to the fraction.
- After isolating \( R \), we get \( IR + Ir = E \), which aligns more closely with a linear format.
- Ultimately, our final equation, \( R = \frac{E - Ir}{I} \), presents \( R \) in a clear, linear manner.