For what value of y is the expression \(\frac{y + 2}{y^{2} - 3y - 10}\)
MATHEMATICS
WAEC 1991
For what value of y is the expression \(\frac{y + 2}{y^{2} - 3y - 10}\) undefined?
- A. y = 0
- B. y = 2
- C. y = 3
- D. y = 5
Correct Answer: D. y = 5
Explanation
\(\frac{y + 2}{y^2 - 3y - 10}\)
\(y^2 - 3y - 10 = 0 \implies y^2 - 5y + 2y - 10 = 0\)
\(y(y - 5) + 2(y - 5) = 0\)
\((y - 5)(y + 2) = 0\)
\(\frac{y + 2}{(y - 5)(y + 2)} = \frac{1}{y - 5}\)
\(\therefore\) At y = 5, the expression \(\frac{y + 2}{y^2 - 3y - 10}\) is undefined.
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