What is the radius of the circle with equation ?
Answer and explanation
Correct answer: D.
.
.
.
- Step 1: Divide the entire equation by 2 to make leading coefficients 1:
- Step 2: Complete the square for and :
- Step 3: Simplify the right side: .
- Step 4: The radius is .
Answer
.
Why not the others: '' forgets to add to the right-hand constant; '' computes without adding the original constant ; '' divides 16 by 2 and adds 5.
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