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X^2-8x+y^2=9 what is the radius

User CEGRD
by
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1 Answer

1 vote

Answer:

5

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 express

x² - 8x + y² = 9 in this form complete the square on the x- terms

x² + 2(- 4) x + (- 4)² + y² = 9 + (- 4)²

(x - 4)² + y² = 9 + 16 = 25 ← in standard form

with centre = (4, 0) and r =
√(25) = 5

User Realtebo
by
8.4k points

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