What is the center and radius of the circle defined by ?
Answer and explanation
Correct answer: A. Center , radius
- Step 1: Complete the square for : .
- Step 2: Complete the square for : .
- Step 3: Substitute back: .
- Step 4: Circle in standard form has center and radius .
Answer
Center (3, -4), radius 5.
Why not the others: The option with center has inverted signs; the option with radius gives instead of ; the option with center uses un-halved coefficients.
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