Chapter 11: Problem 32
Solve each equation. $$4^{3 x}=\left(\frac{1}{2}\right)^{1-x}$$$
Short Answer
Expert verified
The solution is \(x = -0.2\).
Step by step solution
01
Rewrite the Equation with a Common Base
First, recognize that both the left and right sides of the equation can be written with a common base. Notice that \(4 = 2^2\) and \(\frac{1}{2} = 2^{-1}\). Rewrite the equation accordingly:\[4^{3x} = \left(\frac{1}{2}\right)^{1-x} \rightarrow (2^2)^{3x} = (2^{-1})^{1-x}\]
02
Simplify the Exponents
Apply the power rule \((a^m)^n = a^{mn}\) to both sides of the equation:\[2^{6x} = 2^{-(1-x)}\]
03
Set the Exponents Equal
Since the bases are the same, set the exponents equal to each other:\[6x = -(1 - x)\]
04
Solve for x
Solve the equation for \(x\):\[6x = -1 + x \rightarrow 6x - x = -1 \rightarrow 5x = -1 \rightarrow x = \frac{-1}{5} = -0.2\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Common Base
When solving exponential equations, it's often helpful to rewrite the equation using a common base. In this problem, we have the equation \(4^{3x} = \frac{1}{2}^{1-x}\). Notice that the number 4 can be expressed as \(2^2\) and the fraction \(\frac{1}{2}\) can be written as \(2^{-1}\). By rewriting both sides with the common base of 2, the equation becomes easier to manage. This step transforms our equation into \((2^2)^{3x} = (2^{-1})^{1-x}\). Using a common base simplifies the comparison of the exponents.
Exponents
Exponents are the numbers that indicate how many times a base is multiplied by itself. In the equation \((2^2)^{3x} = (2^{-1})^{1-x}\), we use properties of exponents to simplify each side. Specifically, we use the power rule, \((a^m)^n = a^{mn}\).
Applying this rule, the left side simplifies to \(2^{6x}\) and the right side to \(2^{-(1-x)}\). Now we have a new equation: \(2^{6x} = 2^{-(1-x)}\). At this stage, solving the equation becomes more straightforward since the bases are now identical.
Applying this rule, the left side simplifies to \(2^{6x}\) and the right side to \(2^{-(1-x)}\). Now we have a new equation: \(2^{6x} = 2^{-(1-x)}\). At this stage, solving the equation becomes more straightforward since the bases are now identical.
Algebraic Manipulation
Algebraic manipulation involves rearranging and simplifying mathematical expressions. With our new equation \(2^{6x} = 2^{-(1-x)}\), the next step is to set the exponents equal to each other. This is because if \(a^m = a^n\), then it must follow that \(m = n\).
Therefore, we set:\(6x = -(1-x)\). To solve for \(x\), combine like terms and isolate \(x\):
- Add \(x\) to both sides: \(6x + x = -1\)
- Combine: \(7x = -1\)
- Finally, divide by 7: \(x = \frac{-1}{5}\).
Therefore, we set:\(6x = -(1-x)\). To solve for \(x\), combine like terms and isolate \(x\):
- Add \(x\) to both sides: \(6x + x = -1\)
- Combine: \(7x = -1\)
- Finally, divide by 7: \(x = \frac{-1}{5}\).
Equation Solving
Equation solving is the process of finding the value of the variable that makes the equation true. In our case, we started with \(4^{3x} = \frac{1}{2}^{1-x}\) and through a series of steps—rewriting in common bases, simplifying exponents, and algebraic manipulation—we've narrowed it down to the simpler equation \(7x = -1\). To isolate \(x\), we performed basic arithmetic operations:
. Combined like terms:
- Divided both sides by 7:
This gives us the solution \(x = \frac{-1}{5} = -0.2\). At each step, ensuring the accuracy of our manipulations was key to finding the correct value of \(x\).
. Combined like terms:
- Divided both sides by 7:
This gives us the solution \(x = \frac{-1}{5} = -0.2\). At each step, ensuring the accuracy of our manipulations was key to finding the correct value of \(x\).