Which equation is equivalent to (1/3)^x = 27 ^x + 2
The Correct Answer and Explanation is:
We are tasked with solving for ( x ) in the equation:
[
\left(\frac{1}{3}\right)^x = 27^{x+2}
]
Step 1: Express everything with a common base
To solve this equation, we should first express both sides using the same base. We observe that both ( \frac{1}{3} ) and ( 27 ) are powers of 3:
- ( \frac{1}{3} = 3^{-1} )
- ( 27 = 3^3 )
Now we can rewrite the equation as:
[
(3^{-1})^x = (3^3)^{x+2}
]
Step 2: Simplify the exponents
Next, simplify both sides by applying the rule of exponents ( (a^m)^n = a^{m \cdot n} ).
- On the left-hand side: ( (3^{-1})^x = 3^{-x} )
- On the right-hand side: ( (3^3)^{x+2} = 3^{3(x+2)} = 3^{3x+6} )
So the equation becomes:
[
3^{-x} = 3^{3x + 6}
]
Step 3: Set the exponents equal
Since the bases are the same (both are powers of 3), we can set the exponents equal to each other:
[
-x = 3x + 6
]
Step 4: Solve for ( x )
Now solve for ( x ):
- Add ( x ) to both sides:
[
0 = 4x + 6
]
- Subtract 6 from both sides:
[
-6 = 4x
]
- Divide by 4:
[
x = -\frac{3}{2}
]
Final Answer:
The solution to the equation is:
[
x = -\frac{3}{2}
]
Explanation:
To solve the equation, we first expressed both ( \frac{1}{3} ) and ( 27 ) as powers of 3 to make it easier to manipulate the exponents. Once the equation had the same base on both sides, we used the property of exponents that allows us to set the exponents equal to each other. This gave us a simple linear equation to solve for ( x ).