What is the solution to the given equation? (-54)/w = 6...
GMAT Advanced Math : (Adv_Math) Questions
What is the solution to the given equation?
\(\frac{-54}{\mathrm{w}} = 6\)
1. INFER the solution strategy
Given equation: \(\frac{-54}{\mathrm{w}} = 6\)
- Strategy: Since w appears in the denominator of a fraction, we need to eliminate the fraction first by multiplying both sides by w, then isolate w.
- Important note: Since w is in the denominator, \(\mathrm{w} ≠ 0\).
2. SIMPLIFY by eliminating the fraction
- Multiply both sides by w:
\(\frac{-54}{\mathrm{w}} × \mathrm{w} = 6 × \mathrm{w}\)
\(-54 = 6\mathrm{w}\) - This eliminates the fraction and gives us a simpler linear equation.
3. SIMPLIFY by isolating the variable
- Divide both sides by 6:
\(\frac{-54}{6} = \frac{6\mathrm{w}}{6}\)
\(-9 = \mathrm{w}\) - Therefore: \(\mathrm{w} = -9\)
4. Verify the solution
- Check: \(\frac{-54}{-9} = \frac{54}{9} = 6\) ✓
- Also confirm \(\mathrm{w} ≠ 0\): Since \(-9 ≠ 0\), our solution is valid.
Answer: -9
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak SIMPLIFY execution: Sign errors when working with negative numbers
Students often struggle with the arithmetic involving negative numbers, particularly when dividing -54 by 6. They might incorrectly calculate \(\frac{-54}{6} = 9\) instead of \(\frac{-54}{6} = -9\), or make errors when substituting back to check their work.
This leads them to an incorrect answer of \(\mathrm{w} = 9\), which doesn't match any typical wrong answer pattern but causes confusion during verification.
Second Most Common Error:
Poor INFER reasoning: Attempting to solve by cross-multiplication incorrectly
Some students might try to rewrite \(\frac{-54}{\mathrm{w}} = 6\) as \(-54 = 6\mathrm{w}\) immediately without proper justification, or attempt other algebraic manipulations without a clear strategy. This can lead to computational errors or getting stuck mid-solution.
This causes them to abandon systematic solution and resort to guessing.
The Bottom Line:
This problem tests fundamental equation-solving skills with rational expressions. Success requires both strategic thinking (recognizing how to eliminate fractions) and careful arithmetic with negative numbers.