Question

Find the centre and radius of a circle 4x*2+4y*2+8x-12y+20=0

Answer 1

Given equation of the circle is

4x*2+4y*2+8x-12y+20=0

x*2+y*2+2x-3y+5=0

now,. 2g=2. 2f=-3

g=1. f=-3/2

centre (-g,-f)= (-1,3/2)

radius =√g*2+f*2-c

=√ 1+9/4-5

=√-13/4

=√-13/2