The point on the curve y = x³ − 11x + 5 at which the tangent is y = x − 11 is:
The point on the curve y = x³ − 11x + 5 at which the tangent is y = x − 11 is:
- A. (2, −9)
- B. (3, −1)
- C. (4, 13)
- D. (1, −5)
Answer: A) (2, −9)
Explanation: Slope of given tangent is 1. dy/dx = 3x² − 11 = 1 → 3x² = 12 → x² = 4 → x = 2 or −2. For x = 2, y = 8 − 22 + 5 = −9. Tangent at (2, −9): y + 9 = 1(x − 2) → y = x − 11. Matches. For x = −2, y = −8 + 22 + 5 = 19, tangent y − 19 = 1(x + 2) → y = x + 21 ≠ given line.
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