find center, radius of 16x^2 + 16y^2 + 40y - 7 = 0

[Racheljo3]

Find the center and radius of 16x^2 + 16y^2 + 40y - 7 = 0. How would its graph look?

 

[skeeter]

16x² + 16y² + 40y - 7 = 0

divide every term by 16 ...

x² + y² + (5/2)y - 7/16 = 0

x² + y² + (5/2)y = 7/16

complete the square for the quadratic in y ...

x² + y² + (5/2)y + (25/16) = (7/16) + (25/16)

x² + [y + (5/4)]² = 2

so ... what would the graph of this equation be?