Chapter 3: Problem 2
Solve the exponential equations exactly for \(x\). $$169^{x}=13$$
Short Answer
Expert verified
The solution is \(x = \frac{1}{2}\).
Step by step solution
01
Recognize the Relationship Between the Bases
The equation is \(169^x = 13\). Notice that \(169\) can be expressed as \(13^2\). This is because \(169 = 13 \times 13\). This is the key step to solving the equation as we can rewrite the equation with a common base.
02
Rewrite the Equation Using the Common Base
Substitute \(169\) with \(13^2\) in the original equation:\[(13^2)^x = 13\]This simplifies to \(13^{2x} = 13^1\) since raising a power to a power multiplies the exponents.
03
Set the Exponents Equal
Since the bases \(13^{2x}\) and \(13^1\) are the same, we can set the exponents equal to each other:\[2x = 1\]
04
Solve for x
Solve the equation \(2x = 1\) by dividing both sides by 2:\[x = \frac{1}{2}\]This gives the exact solution for \(x\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponentiation
Exponentiation is a mathematical operation where a number, known as the base, is raised to a certain power, which is called the exponent. When we write something like \(b^n\), we are saying that the base \(b\) is multiplied by itself \(n\) times. This makes exponential form a convenient way to express very large or very small numbers. For example:
- \(2^3 = 2 \times 2 \times 2 = 8\)
- \(5^4 = 5 \times 5 \times 5 \times 5 = 625\)
- The base raised to the power of zero is always 1: \(b^0 = 1\) for any non-zero \(b\).
- A base raised to the power of one is the base itself: \(b^1 = b\).
- When you multiply powers with the same base, you add the exponents: \(b^m \times b^n = b^{m+n}\).
- When you raise a power to another power, you multiply the exponents: \((b^m)^n = b^{m \cdot n}\).
Common Base
The concept of a common base is crucial in solving exponential equations, like the problem \(169^x = 13\). The idea is to express all terms in the equation with the same base, if possible. Let's see how this helps identify the solution:
- First, recognize the relationship between the numbers. Notice that 169 is actually \(13^2\), which gives us a common base of 13 for both sides of the equation.
- Rewriting \(169^x\) as \((13^2)^x\) helps simplify the equation, turning it into \(13^{2x}\). Now, you deal with exponents more easily.
Solving Equations
Solving equations, especially exponential ones, requires a clear strategy. Consider the exponential equation \(169^x = 13\). Similar to other equations, the goal is to isolate \(x\).
Here's the step-by-step approach:
Here's the step-by-step approach:
- Recognize any shared bases and express all terms with this base, as was done when identifying \(169 = 13^2\).
- Set the exponents equal once you have the same base on both sides of the equation. This works because if \(b^m = b^n\), then \(m = n\).
- Solve the simpler resulting equation for \(x\). For \(13^{2x} = 13^1\), you set \(2x = 1\).
- Finally, solve for \(x\) by dividing both sides by the necessary coefficient. Here, you divide by 2 to find \(x = \frac{1}{2}\).