Question

What is the equation of the circle in general form?

A. x² + y² + 2x + 8y − 47 = 0

B. x²+y² − 2x − 8y + 9 = 0

C. x² + y² + 2x + 8y + 9 = 0

D. x² + y² − 2x − 8y − 47 = 0

Please Explain Your Answer, Thank You ^-^

Answer 1

d.

the equation for a circle is 
$(x-h)^2 + (y-k)^2=r^2$

with the point (h,k) being the center of the circle, and radius r.

your circle is centered at (1,4) and a radius of 8. plugging those in you get the equation
$(x-1)^2+(y-4)^2=8^2 \\ (x^2-2x+1)+(y^2-8x+16) = 64 \\ x^2+y^2-2x-8y+17=64 \\ x^2+y^2-2x-8y-47=0$

Answer 2

Answer:

D

I took the test :)