\((7532 + 100\mathrm{y}^2) + 10(10\mathrm{y}^2 - 110)\)The expression above can be written in the form ay^2 + b, where a...
GMAT Advanced Math : (Adv_Math) Questions
\((7532 + 100\mathrm{y}^2) + 10(10\mathrm{y}^2 - 110)\)
The expression above can be written in the form \(\mathrm{ay}^2 + \mathrm{b}\), where \(\mathrm{a}\) and \(\mathrm{b}\) are constants. What is the value of \(\mathrm{a} + \mathrm{b}\)?
1. TRANSLATE the problem requirements
- Given: \((7532 + 100\mathrm{y}^2) + 10(10\mathrm{y}^2 - 110)\)
- Need to: Express in form \(\mathrm{ay}^2 + \mathrm{b}\) and find \(\mathrm{a} + \mathrm{b}\)
- What this tells us: We need to simplify the expression to clearly see the coefficient of \(\mathrm{y}^2\) and the constant term
2. SIMPLIFY using the distributive property
- Apply distributive property to the second term: \(10(10\mathrm{y}^2 - 110)\)
- \(10 \times 10\mathrm{y}^2 = 100\mathrm{y}^2\)
- \(10 \times (-110) = -1100\)
- Result: \((7532 + 100\mathrm{y}^2) + (100\mathrm{y}^2 - 1100)\)
3. SIMPLIFY by combining like terms
- Remove parentheses: \(7532 + 100\mathrm{y}^2 + 100\mathrm{y}^2 - 1100\)
- Group like terms: \((100\mathrm{y}^2 + 100\mathrm{y}^2) + (7532 - 1100)\)
- Combine \(\mathrm{y}^2\) terms: \(200\mathrm{y}^2\)
- Combine constants: \(6432\)
- Final expression: \(200\mathrm{y}^2 + 6432\)
4. TRANSLATE to identify a and b values
- In the form \(\mathrm{ay}^2 + \mathrm{b}\), we have: \(\mathrm{a} = 200\) and \(\mathrm{b} = 6432\)
- Therefore: \(\mathrm{a} + \mathrm{b} = 200 + 6432 = 6632\)
Answer: 6632
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak SIMPLIFY execution: Students make arithmetic errors when applying the distributive property, particularly with the negative sign.
For example, they might calculate \(10(-110) = -110\) instead of \(-1100\), leading to:
\(200\mathrm{y}^2 + (7532 - 110) = 200\mathrm{y}^2 + 7422\)
This gives \(\mathrm{a} + \mathrm{b} = 200 + 7422 = 7622\), which is incorrect.
Second Most Common Error:
Incomplete SIMPLIFY process: Students correctly apply the distributive property but fail to properly combine like terms.
They might stop at \((7532 + 100\mathrm{y}^2) + (100\mathrm{y}^2 - 1100)\) without recognizing they need to collect the \(\mathrm{y}^2\) terms together to get the standard form. This leads to confusion about which values represent a and b.
The Bottom Line:
This problem tests systematic algebraic manipulation skills. Success requires careful attention to sign changes during distribution and methodical combination of like terms to achieve the required form.