How do you graph x^2+y^2-2x-4y-20=0?
1 Answer
Jul 28, 2016
This is a circle with centre
Explanation:
Complete the square for both
0 = x^2+y^2-2x-4y-20
= color(blue)(x^2-2x+1)+color(green)(y^2-4y+4)-25
= (x-1)^2+(y-2)^2-5^2
Add
(x-1)^2+(y-2)^2=5^2
This is in the form:
(x-h)^2+(y-k)^2=r^2
the equation of a circle with centre
graph{((x-1)^2+(y-2)^2-25)((x-1)^2+(y-2)^2-0.01) = 0 [-9.04, 10.96, -2.76, 7.24]}