Hey, i'm trying to solve this and im confused by the 2x and 2y. How do I treat this problem?
Thanks guys.
$\displaystyle 2x^2+2y^2+18x+4=0$
First divide the equation through by 2:
$\displaystyle x^2+y^2+9x+2=0$
Subtract 2 from both sides:
$\displaystyle x^2+y^2+9x=-2$
Group the x terms together:
$\displaystyle (x^2+9x)+y^2=-2$
Complete the square:
$\displaystyle \left(x^2+9x+\tfrac{81}{4}\right)+y^2=-2+\tfrac{81}{4}$
$\displaystyle \left(x+\tfrac{9}{2}\right)^2+y^2=\tfrac{77}{4}$
Thus, the center of the circle is ........
The radius of the circle is ........
I hope this helps!
--Chris