We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. cookie policy and privacy policy.
 
+0  
 
-1
55
1
avatar+1028 

The center of the circle with equation \(x^2+y^2=8x-6y-20\) is the point \((x,y)\). What is \(x+y\)?

 Jul 15, 2019
 #1
avatar+102386 
+1

Rearrange  as

 

x^2 - 8x + y^2 + 6y  = -20       complete the square on x and y

 

x^2 - 8x + 16  + y^2 + 6y + 9  =  -20 + 16  + 9

 

(x - 4)^2  + ( y + 3)^2  =  5

 

The center is  ( 4, -3)  =  ( x , y)

 

So    

 

x + y   =   4 + (-3)   =    1

 

 

cool cool cool

 Jul 15, 2019

15 Online Users

avatar