For what positive value of does have equal roots?

Answer and explanation

Correct answer: D.

  1. Step 1: Equal roots need : .
  2. Step 2: So and the positive value is .
Answer
.
Why not the others: is what you get if you set the discriminant to but forget to double. is what you get if you choose the negative root of . is what you get if you give instead of .

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