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Answer:
the correct answer is marked
Step-by-step explanation:
The circle with center (h, k) and radius r has equation ...
(x -h)² +(y-k)² = r²
For the given center, that is ...
(x -1)² +(y +1)² = r²
The value of r² can be found by using the given point for x and y, and seeing what value of r² makes the equation true.
(5 -1)² +(7 +1)² = 4² +8² = 16 +64 = 80
So, r² = 80 makes the equation true, and that equation is ...
(x -1)² +(y +1)² = 80
