The line is a tangent to the curve . What is the positive value of ?
Answer and explanation
Correct answer: B.
- Step 1: Set equal: . A tangent gives discriminant .
- Step 2: so , giving or .
- Step 3: The positive value is .
Answer
.
Why not the others: The discriminant of is . It is for and for (no contact) and and for and (two intersections), so none of these gives a tangent.
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