What is the equation of the circle in standard form?

Question

1.) x^2 + y^2 + 4x -8y + 4 = 0. 

2.) What are the foci of the ellipse: (x-1)^2/4 + (y+2)^2/9 = 1? 

3.) What is the general form equation of the circle: (x-1)^2 + (y-5)^2 = 49? 

4.) Find the sum of the first twelve terms of the arithmetic series: An = -2n + 1?

Answer 1

1.The given circle euation is