What value of x is the solution to the equation 16x + 24 = 24x?
GMAT Algebra : (Alg) Questions
What value of x is the solution to the equation \(16\mathrm{x} + 24 = 24\mathrm{x}\)?
1. INFER the solving strategy
- Given: \(16\mathrm{x} + 24 = 24\mathrm{x}\)
- Goal: Isolate x on one side of the equation
- Strategy: First eliminate x terms from one side, then divide by the remaining coefficient
2. SIMPLIFY by collecting like terms
- Subtract 16x from both sides:
- Left side: \(16\mathrm{x} + 24 - 16\mathrm{x} = 24\)
- Right side: \(24\mathrm{x} - 16\mathrm{x} = 8\mathrm{x}\)
- Result: \(24 = 8\mathrm{x}\)
3. SIMPLIFY by isolating x
- Divide both sides by 8:
- \(24 \div 8 = 3\)
- \(8\mathrm{x} \div 8 = \mathrm{x}\)
- Result: \(\mathrm{x} = 3\)
Answer: D. 3
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak SIMPLIFY skill: Confusing which coefficient to divide by or making arithmetic errors during the division step.
After correctly getting to \(24 = 8\mathrm{x}\), some students might think "x equals the coefficient divided by the constant" and calculate \(\mathrm{x} = 8/24 = 1/3\) instead of \(\mathrm{x} = 24/8 = 3\). This reverses the division operation.
This may lead them to select Choice C (1/3).
Second Most Common Error:
Poor SIMPLIFY execution: Making sign errors or calculation mistakes when combining like terms.
Students might incorrectly subtract terms or make arithmetic errors, leading to equations like \(-8\mathrm{x} = -32\) (giving \(\mathrm{x} = 4\), not among choices) or other incorrect intermediate steps that cause confusion and guessing.
The Bottom Line:
This problem tests whether students can systematically apply inverse operations while maintaining accuracy in basic arithmetic - the foundation of algebraic equation solving.