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Find the center and the radius of the circle x^2+y^2+6x-4y-12=0 show your work

User MHP
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1 Answer

6 votes

Answer:

see explanation

Explanation:

the equation of a circle in standard form is

(x - h)² + (y - k)² = r²

where (h, k) are the coordinates of the centre and r is the radius

To obtain this form use the method of completing the square on both the x and y terms

rearranging

x² + 6x + y² - 4y = 12

x² + 2(3)x + 9 + y² + 2(- 2)y + 4 = 12 + 9 + 4

(x + 3)² + (y - 2)² = 25 ← in standard form

with centre = (- 3, 2) and r =
√(25) = 5


User Kingston Chan
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