Tangent Line to a Parabola
Easytangent linederivatives
Find the line tangent to at
- Ay = 3x − 7
- By = 3x + 2
- Cy = 2x − 4
- Dy = 6x − 16
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Answer: A. y = 3x − 7
The point of tangency is y(3) = 9 − 9 + 2 = 2, so (3, 2). The slope is y′ = 2x − 3, which is 3 at x = 3. Point-slope form: y − 2 = 3(x − 3), so y = 3x − 7. Check: 3(3) − 7 = 2. TI-36X Pro tip: press 2nd, d/dx, enter x² − 3x + 2 in the first box, move right to the last box, enter 3, and press enter. The slope is 3. Then check the answer line passes through (3, 2).
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