# How do you graph # x² + y² + 4x - 4y - 17 = 0#?

##### 1 Answer

Apr 24, 2016

This is a circle with centre

#### Explanation:

#0 = x^2+y^2+4x-4y-17#

#=x^2+4x+4+y^2-4y+4-25#

#=(x+2)^2+(y-2)^2-5^2#

Add

#(x+2)^2+(y-2)^2=5^2#

This is (almost) in the form:

#(x-h)^2+(y-k)^2=r^2#

which is the standard form of the equation of a circle centre

Hence we find

This is a circle with centre

graph{((x+2)^2+(y-2)^2-5^2)((x+2)^2+(y-2)^2-0.03) = 0 [-11, 11, -3.7, 7.2]}