Advanced MathVery hardReducing a rational expression to a constant over x
Advanced Math practice question
For x ≠ 0 and x ≠ −3, the expression (2x + 6)/(x² + 3x) is equivalent to k/x, where k is a constant. What is the value of k?
Answer: 2
2x + 6 = 2(x + 3) and x² + 3x = x(x + 3). Cancelling x + 3 leaves 2/x.
Common wrong answers
- If you answered 1
- 1 forgets the factor 2 in the numerator.
- If you answered 3
- 3 copies the constant from x + 3.
- If you answered 6
- 6 copies the constant from the numerator.
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