\(\mathrm{g(x) = 32(2^x)}\) Which table gives three values of x and their corresponding values of \(\mathrm{g(x)}\) for function g?...
GMAT Advanced Math : (Adv_Math) Questions
\(\mathrm{g(x) = 32(2^x)}\)
Which table gives three values of \(\mathrm{x}\) and their corresponding values of \(\mathrm{g(x)}\) for function g?
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(-64\) |
| \(0\) | \(0\) |
| \(1\) | \(64\) |
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(\frac{1}{16}\) |
| \(0\) | \(2\) |
| \(1\) | \(64\) |
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(\frac{1}{16}\) |
| \(0\) | \(32\) |
| \(1\) | \(64\) |
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(16\) |
| \(0\) | \(32\) |
| \(1\) | \(64\) |
1. TRANSLATE the problem information
- Given function: \(\mathrm{g(x) = 32(2^x)}\)
- Need to: Find g(x) values for x = -1, 0, and 1
- What this means: Substitute each x value into the function and compute the result
2. SIMPLIFY by evaluating each case
For x = -1:
- \(\mathrm{g(-1) = 32(2^{-1})}\)
- Since \(\mathrm{2^{-1} = \frac{1}{2}}\)
- \(\mathrm{g(-1) = 32 \times \frac{1}{2} = 16}\)
For x = 0:
- \(\mathrm{g(0) = 32(2^0)}\)
- Since \(\mathrm{2^0 = 1}\)
- \(\mathrm{g(0) = 32 \times 1 = 32}\)
For x = 1:
- \(\mathrm{g(1) = 32(2^1)}\)
- Since \(\mathrm{2^1 = 2}\)
- \(\mathrm{g(1) = 32 \times 2 = 64}\)
3. APPLY CONSTRAINTS to select the matching table
- Our computed values: \(\mathrm{(-1, 16), (0, 32), (1, 64)}\)
- Only Choice D matches all three values
Answer: D
Why Students Usually Falter on This Problem
Most Common Error Path:
Conceptual gap with exponent rules: Students often forget that \(\mathrm{2^{-1} = \frac{1}{2}}\), thinking instead that negative exponents make the whole result negative, or they might compute \(\mathrm{2^{-1} = -2}\).
This leads to \(\mathrm{g(-1) = 32(-2) = -64}\), making them select Choice A (-64).
Second Most Common Error:
Conceptual confusion about zero exponents: Students sometimes think \(\mathrm{2^0 = 0}\) instead of \(\mathrm{2^0 = 1}\).
This leads to \(\mathrm{g(0) = 32(0) = 0}\), which combined with other errors might make them select Choice A or causes confusion leading to guessing.
The Bottom Line:
This problem tests whether students truly understand exponent rules in a function context. The key insight is recognizing that negative and zero exponents follow specific rules that must be applied before multiplying by the coefficient 32.
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(-64\) |
| \(0\) | \(0\) |
| \(1\) | \(64\) |
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(\frac{1}{16}\) |
| \(0\) | \(2\) |
| \(1\) | \(64\) |
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(\frac{1}{16}\) |
| \(0\) | \(32\) |
| \(1\) | \(64\) |
| \(\mathrm{x}\) | \(\mathrm{g(x)}\) |
|---|---|
| \(-1\) | \(16\) |
| \(0\) | \(32\) |
| \(1\) | \(64\) |