Question 223 of 480
Given that 3√42x = 16, find the value of x
Correct Answer:
C
Explanation
To solve the equation \( \sqrt[3]{4^{2x}} = 16 \), we will follow a step-by-step approach to isolate \( x \) and find its value.
### Step 1: Rewrite the Equation
The equation given is:
\[
\sqrt[3]{4^{2x}} = 16
\]
We can rewrite the left side using the property of exponents. The cube root can be expressed as an exponent:
\[
4^{2x} = 16^3
\]
### Step 2: Simplify the Right Side
Next, we need to simplify \( 16^3 \). We know that \( 16 \) can be expressed as a power of \( 4 \):
\[
16 = 4^2
\]
Thus, we can rewrite \( 16^3 \) as:
\[
16^3 = (4^2)^3 = 4^{2 \cdot 3} = 4^6
\]
### Step 3: Set the Exponents Equal
Now we have:
\[
4^{2x} = 4^6
\]
Since the bases are the same (both are base \( 4 \)), we can set the exponents equal to each other:
\[
2x = 6
\]
### Step 4: Solve for \( x \)
To find \( x \), we divide both sides of the equation by \( 2 \):
\[
x = \frac{6}{2} = 3
\]
### Conclusion
Thus, the value of \( x \) is \( 3 \).
### Verification
To ensure our solution is correct, we can substitute \( x = 3 \) back into the original equation:
\[
\sqrt[3]{4^{2 \cdot 3}} = \sqrt[3]{4^6}
\]
Calculating \( 4^6 \):
\[
4^6 = 4096
\]
Now, taking the cube root:
\[
\sqrt[3]{4096} = 16
\]
This confirms that our solution is correct since both sides of the equation are equal.
### Explanation of Other Options
- **Option A: 4** - If \( x = 4 \), then \( 2x = 8 \) and \( 4^{2x} = 4^8 \), which does not equal \( 16 \).
- **Option B: 6** - If \( x = 6 \), then \( 2x = 12 \) and \( 4^{2x} = 4^{12} \), which is much larger than \( 16 \).
- **Option D: 2** - If \( x = 2 \), then \( 2x = 4 \) and \( 4^{2x} = 4^4 = 256 \), which is also not equal to \( 16 \).
### Revision Summary
- To solve equations involving roots and exponents, rewrite them in terms of the same base.
- Set the exponents equal when the bases are the same.
- Always verify your solution by substituting back into the original equation.
- Be cautious with exponent rules and ensure calculations are accurate.
The correct answer is **C. 3**.