SOLUTION: Write the equation of the circle in standard form.  Find the center, radius, intercepts, and graph the circle. x^2+y^2+8x+2y+8=0 I am having trouble with the steps involved.

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Write the equation of the circle in standard form.  Find the center, radius, intercepts, and graph the circle. x^2+y^2+8x+2y+8=0 I am having trouble with the steps involved.      Log On


   

Question 636257: Write the equation of the circle in standard form.  Find the center, radius, intercepts, and graph the
circle.
x^2+y^2+8x+2y+8=0
I am having trouble with the steps involved.
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Write the equation of the circle in standard form. Find the center, radius, intercepts, and graph the
circle.
x^2+y^2+8x+2y+8=0
**
Standard form of equation for a circle: %28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2, (h,k)=(x,y) coordinates of center, r=radius.
x^2+y^2+8x+2y+8=0
complete the square
x^2+8x+y^2+2y+8=0
(x^2+8x+16)+(y^2+2y+1)=-8+16+1
Equation:
%28x%2B4%29%5E2%2B%28y%2B1%29%5E2=9
..
r^2=9
radius=3
..
center:(-4,-1)
..
x-intercepts:
set y=0
(x+4)^2+1=9
(x+4)^2=8
x+4=±√8
x=-4±√8
x≈-6.83
or
x≈-1.17
..
See graph below:
y=±(9-(x+4)^2)^.5-1