Advanced MathMediumEvaluating a rational expression after simplifying
Advanced Math practice question
For x ≠ −3/2, the expression (4x² − 9)/(2x + 3) simplifies to a linear expression. What is the value of that expression when x = 10?
Answer: 17
4x² − 9 = (2x − 3)(2x + 3), so the expression equals 2x − 3. At x = 10: 20 − 3 = 17.
Common wrong answers
- If you answered 7
- 7 is 10 − 3, forgetting the factor 2.
- If you answered 23
- 23 is 2x + 3, cancelling the wrong factor.
- If you answered 391
- 391 is 4(100) − 9, the numerator alone.
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