Simplify (x^2 - 9)/(x^2 + x - 12) and state the restrictions.
Answer and explanation
Correct answer: A. (x + 3)/(x + 4), with x not equal to 3 or -4
- Step 1: Factor: (x - 3)(x + 3) over (x + 4)(x - 3). Step 2. Cancel x - 3 to get (x + 3)/(x + 4); the original denominator is zero at x = 3 and x = -4. Answer: (x + 3)/(x + 4), x not 3 or -4. Why not the others: the others mis-cancel a factor or drop the restriction created by the cancelled factor.
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