Chapter 8: Problem 43
Solve each system of exponential or logarithmic equations. $$\begin{aligned} &y=3^{x}\\\ &y=2^{x} \end{aligned}$$
Short Answer
Expert verified
x = 0.
Step by step solution
01
Set Equations Equal
Given the system of equations:y = 3^xy = 2^xSince both expressions are equal to y, set them equal to each other:3^x = 2^x
02
Take the Logarithm of Both Sides
Apply logarithms to both sides of the equation. Using the natural logarithm (ln) for convenience:\( \text{ln}(3^x) = \text{ln}(2^x) \)
03
Use Logarithmic Properties
Apply the power rule of logarithms, which states \( \text{ln}(a^b) = b \text{ln}(a) \):\( x \text{ln}(3) = x \text{ln}(2) \)
04
Simplify the Equation
Divide both sides of the equation by \( x \) to isolate the natural logarithms:\( \text{ln}(3) = \text{ln}(2) \)
05
Solve for x
Since \( \text{ln}(3) \) and \( \text{ln}(2) \) are distinct values, the only solution satisfying this equality is:\( x = 0 \)
06
Verify the Solution
To verify, substitute \( x = 0 \) back into the original equations:\( y = 3^0 = 1 \)\( y = 2^0 = 1 \)Both verifications give y = 1, so the solution is confirmed.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
System of Equations
A system of equations consists of two or more equations with the same variables. In our case, we had the equations:
- y = 3^x
- y = 2^x
Natural Logarithm
The natural logarithm, denoted as `ln`, is a logarithm with base `e`, where `e ≈ 2.71828`. It's a very useful function because of its properties, especially in calculus and solving exponential equations.
When we have `3^x = 2^x`, applying the natural logarithm on both sides converts the exponential form into a linear form. This is why we write:
When we have `3^x = 2^x`, applying the natural logarithm on both sides converts the exponential form into a linear form. This is why we write:
- ln(3^x) = ln(2^x)
Logarithmic Properties
Logarithmic properties help in transforming and simplifying equations involving exponents. Two important properties we used here are:
- Power Rule: ln(a^b) = b * ln(a)
- Log of a Product: ln(a * b) = ln(a) + ln(b)
- ln(3^x) = x * ln(3)
- ln(2^x) = x * ln(2)
Power Rule of Logarithms
The power rule of logarithms states that for any numbers `a` and `b`, ln(a^b) = b * ln(a). This rule is particularly useful for dealing with exponents in logarithmic equations. In our problem:
When we simplify further, we see that dividing both sides by `x` (as long as `x` ≠0) gives us `ln(3) = ln(2)`, which is not true. So, the only valid solution is `x = 0`, confirming our initial setup.
- ln(3^x) becomes x * ln(3)
- ln(2^x) becomes x * ln(2)
When we simplify further, we see that dividing both sides by `x` (as long as `x` ≠0) gives us `ln(3) = ln(2)`, which is not true. So, the only valid solution is `x = 0`, confirming our initial setup.