In the general form of a conic with no xy term, A equals 5 and C equals 5. Which curve is it?

1. Write the equation as Ax squared plus Cy squared plus Dx plus Ey plus F equals 0. 2. Both A and C are nonzero and both equal 5, so they match in size and in sign. 3. Equal nonzero coefficients of the same sign make the graph a circle. 4. An ellipse needs A and C to share a sign but differ in size, which fails here. _Source: OpenStax College Algebra (CC BY 4.0), Ch 8 "Analytic Geometry", section 8.4 Rotation of Axes_