The point \((-3, 5)\) in the xy-plane is a solution to which of the following systems of inequalities?
GMAT Algebra : (Alg) Questions
1. TRANSLATE the point information
- Given information:
- Point \((-3, 5)\) where \(-3\) is the x-coordinate and \(5\) is the y-coordinate
- What this tells us:
- \(\mathrm{x = -3}\) (negative value)
- \(\mathrm{y = 5}\) (positive value)
2. TRANSLATE coordinates into inequality conditions
- Since \(\mathrm{x = -3}\) and \(-3\) is negative: \(\mathrm{x \lt 0}\)
- Since \(\mathrm{y = 5}\) and \(5\) is positive: \(\mathrm{y \gt 0}\)
- Our point satisfies: \(\mathrm{x \lt 0}\) AND \(\mathrm{y \gt 0}\)
3. INFER the systematic checking approach
- We need to find which answer choice matches both conditions
- Each answer choice has two parts connected by "and" - both must be true
4. Check each answer choice systematically
- (A) \(\mathrm{x \gt 0}\) and \(\mathrm{y \gt 0}\): Does \(\mathrm{-3 \gt 0}\)? No. This fails immediately.
- (B) \(\mathrm{x \gt 0}\) and \(\mathrm{y \lt 0}\): Does \(\mathrm{-3 \gt 0}\)? No. This fails immediately.
- (C) \(\mathrm{x \lt 0}\) and \(\mathrm{y \gt 0}\): Does \(\mathrm{-3 \lt 0}\)? Yes. Does \(\mathrm{5 \gt 0}\)? Yes. Both true!
- (D) \(\mathrm{x \lt 0}\) and \(\mathrm{y \lt 0}\): Does \(\mathrm{-3 \lt 0}\)? Yes. Does \(\mathrm{5 \lt 0}\)? No. This fails.
Answer: C
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak TRANSLATE skill: Confusing the order of coordinates or misinterpreting inequality symbols
Students might think that because they see negative numbers, they need \(\mathrm{x \lt 0}\) and \(\mathrm{y \lt 0}\), not realizing that the y-coordinate \((5)\) is actually positive. Or they might confuse which coordinate is x and which is y.
This may lead them to select Choice D (\(\mathrm{x \lt 0}\) and \(\mathrm{y \lt 0}\)).
Second Most Common Error:
Incomplete INFER reasoning: Only checking one condition instead of both
Students might see that \(\mathrm{x \lt 0}\) is satisfied and stop there, not verifying that the y-condition also matches. They might pick the first choice where \(\mathrm{x \lt 0}\) is true without checking the y-condition.
This could lead to selecting Choice D or cause confusion between C and D.
The Bottom Line:
This problem requires careful attention to both the signs of coordinates AND the logical structure of compound inequalities with "and" - both conditions must be satisfied simultaneously.