\(\mathrm{g(x) = 11x + 4}\). For the given linear function g, which table shows three values of x and their...
GMAT Algebra : (Alg) Questions
\(\mathrm{g(x) = 11x + 4}\). For the given linear function g, which table shows three values of x and their corresponding values of \(\mathrm{g(x)}\)?
| x | g(x) |
|---|---|
| -1 | 7 |
| 0 | 11 |
| 1 | 15 |
| x | g(x) |
|---|---|
| -1 | -4 |
| 0 | 0 |
| 1 | 4 |
| x | g(x) |
|---|---|
| -1 | -7 |
| 0 | 4 |
| 1 | 15 |
| x | g(x) |
|---|---|
| -1 | -11 |
| 0 | 0 |
| 1 | 11 |
1. TRANSLATE the problem requirements
- Given information:
- Function: \(\mathrm{g(x) = 11x + 4}\)
- Need to find which table shows correct \(\mathrm{g(x)}\) values for \(\mathrm{x = -1, 0,}\) and \(\mathrm{1}\)
- What this tells us: We need to evaluate the function at these three specific x-values
2. INFER the solution strategy
- To determine the correct table, calculate \(\mathrm{g(x)}\) for each x-value
- Compare our calculated results to what each table shows
- The matching table will be our answer
3. SIMPLIFY by evaluating the function at each x-value
For \(\mathrm{x = -1}\):
\(\mathrm{g(-1) = 11(-1) + 4}\)
\(\mathrm{= -11 + 4}\)
\(\mathrm{= -7}\)
For \(\mathrm{x = 0}\):
\(\mathrm{g(0) = 11(0) + 4}\)
\(\mathrm{= 0 + 4}\)
\(\mathrm{= 4}\)
For \(\mathrm{x = 1}\):
\(\mathrm{g(1) = 11(1) + 4}\)
\(\mathrm{= 11 + 4}\)
\(\mathrm{= 15}\)
4. Compare results to the tables
Our calculations show: \(\mathrm{(-1, -7), (0, 4), (1, 15)}\)
Checking each choice:
- Choice A shows \(\mathrm{(-1, 7)}\) but we got \(\mathrm{(-1, -7)}\) ❌
- Choice B shows \(\mathrm{(-1, -4)}\) but we got \(\mathrm{(-1, -7)}\) ❌
- Choice C shows \(\mathrm{(-1, -7), (0, 4), (1, 15)}\) - perfect match! ✅
- Choice D shows \(\mathrm{(-1, -11)}\) but we got \(\mathrm{(-1, -7)}\) ❌
Answer: C
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak SIMPLIFY execution: Sign errors when working with negative numbers
When calculating \(\mathrm{g(-1) = 11(-1) + 4}\), students often make one of these mistakes:
- Calculate \(\mathrm{11(-1) = 11}\) instead of \(\mathrm{-11}\) (forgetting negative times positive = negative)
- Get confused about \(\mathrm{-11 + 4}\) and calculate \(\mathrm{-15}\) instead of \(\mathrm{-7}\)
This leads them to select Choice A (which shows \(\mathrm{g(-1) = 7}\)) if they calculated \(\mathrm{11(-1) + 4 = 11 + 4 = 15}\), then confused the sign.
Second Most Common Error:
Incomplete SIMPLIFY process: Forgetting to add the constant term
Students correctly calculate the \(\mathrm{11x}\) part but forget to add 4:
- \(\mathrm{g(-1) = 11(-1) = -11}\) (forgetting the \(\mathrm{+4}\))
- \(\mathrm{g(0) = 11(0) = 0}\) (forgetting the \(\mathrm{+4}\))
- \(\mathrm{g(1) = 11(1) = 11}\) (forgetting the \(\mathrm{+4}\))
This may lead them to select Choice D which shows these "incomplete" values.
The Bottom Line:
This problem tests careful arithmetic execution more than conceptual understanding. The strategy is straightforward, but students must be methodical with signs and remember all parts of the function formula.
| x | g(x) |
|---|---|
| -1 | 7 |
| 0 | 11 |
| 1 | 15 |
| x | g(x) |
|---|---|
| -1 | -4 |
| 0 | 0 |
| 1 | 4 |
| x | g(x) |
|---|---|
| -1 | -7 |
| 0 | 4 |
| 1 | 15 |
| x | g(x) |
|---|---|
| -1 | -11 |
| 0 | 0 |
| 1 | 11 |