Find the equation of the circle with centre (-3,4) and passing through the origin.

The  radius  =   sqrt [ (0 +3)^2  + ( 0 - 4)^2 ] = sqrt [ 9 + 16 ] = sqrt (25)  = 5

So...the equation becomes

(x + 3)^2 + ( y - 4)^2  =  5^2

(x + 3)^2 + ( y - 4)^2  =  25