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The equation x2+y2+4x−8y=13
describes a circle. Which equation describes the same circle?

(x+2)2+(y−4)2=33

(x+2)2+(y−4)2=13

(x−2)2+(y−4)2=33

(x−2)2+(y−4)2=13



Answer :

Answer:

first option

Step-by-step explanation:

The equation of a circle in standard form is

• (x - h)² + (y - k)² = r²

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

given the general equation

x² + y² + 4x - 8y = 13 ( collect x and y terms together )

x² + 4x + y² - 8y = 13

To express in standard form use the method of completing the square

add ( half the coefficient of the x and y terms)² to both sides

x² + 2(2)x + 4 + y² + 2(- 4)y + 16 = 13 + 4 + 16

(x + 2)² + (y - 4)² = 33 ← in standard form

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