Question 141395
dividing by 5 __ x^2+y^2-25=0 __ adding 25 __ x^2+y^2=25 __ (0,0); r=5



completing the squares __ x^2-14x+49+y^2+8y+16+1=49+16


subtracting 1 __ (x-7)^2+(y+4)^2=64 __ (7,-4); r=8