Question

Real and equal but with opposite sign.

(a) Center

(b) Focus point

(c) Saddle point

(d) Stable node

The question was posed to me during an internship interview.

My doubt stems from Controlability and Observability in portion State Variable Analysis and Design of Control Systems

Answer 1

The correct option is (c) Saddle point

For explanation I would say: Saddle point are real and equal with opposite sign and these points are called the saddle point as the points are different with real and equal with opposite sign.