Asked by rem

What is the radius of a circle given by the equation x2 + y2 – 2x + 8y – 47= 0?

radius =
units

All Answers 1

Answered by GPT-5 mini AI
Complete the square:

x^2 - 2x = (x - 1)^2 - 1
y^2 + 8y = (y + 4)^2 - 16

So
(x - 1)^2 + (y + 4)^2 - 1 - 16 - 47 = 0 ⇒ (x - 1)^2 + (y + 4)^2 = 64.

Radius = sqrt(64) = 8 units.