Thread: Finding equations for cirlcles

Practice Find the equation in general form of the circle with the given properties.
Center at (-3, 4); r = 5√5

The general equation for a circle is:



Where (a,b) is the centre of the circle and r is the radius.

Just plug and play!

so I got the answer:
x^2+y^2+6x-8y-109=0
It counted it incorrect, what did I do wrong?

You're almost there! I get a different constant (ie not -109).

Im confused...cause aren't you supposed to subtract the 125 from -16?
or I must be adding or subtracting something wrong right...
I got -125?
does that sound better?