Question

HELP, 35 POINTS! What is the equation of the circle in general form?

A. x2 + y2 + 4x + 2y − 44 = 0

B. x2 + y2 − 4x − 2y − 2 = 0

C. x2 + y2 + 4x + 2y − 2 = 0

D. x2 + y2 − 4x − 2y − 44 = 0

Answer 1

i think its c.

C. x2 + y2 + 4x + 2y − 2 = 0

Answer 2

The equation of the given circle in general form is given by:

Option: A

`x^2+y^2+4x+2y-44=0`

Explanation:

We know that the general equation of a circle with center at (h,k) and radius 'r' is given by:

`(x-h)^2+(y-k)^2=r^2`

Clearly from the figure we have:

The center of the circle is at (-2,-1) and radius is 7 units.

i.e. we have: (h,k)=(-2,-1) and r=7

Hence, the equation of the circle is given by:

`(x-(-2))^2+(y-(-1))^2=7^2\\\\\\(x+2)^2+(y+1)^2=49`

on expanding the terms we have:

`x^2+4+4x+y^2+1+2y=49\\\\\\x^2+y^2+4x+2y+5-49=0\\\\\\x^2+y^2+4x+2y-44=0`

Hence, the general equation of the circle is:

`x^2+y^2+4x+2y-44=0`