Find the coordinates of the focus of the parabola y² = 16x.
Answer and explanation
Correct answer: A. (4, 0)
- Step 1: Compare with y² = 4ax: here 4a = 16, so a = 4. Step 2. The focus is (a, 0) = (4, 0). Answer: (4, 0). Why not the others: (16, 0) is what you get if you read the focus from the coefficient 4a. (0, 4) is what you get if you swap the coordinates. (8, 0) is what you get if you double the focal length.
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