Let Ak be 2×2 matrices over R, and let fk(x)=Akx, k=1,2.
(a) Assume that the origin is asymptotically stable for f1. Prove that there exists a δ>0 (depending on A1) such that if ∥A1−A2∥<δ, then the origin is asymptotically stable for f2.
(b) Is the preceding statement true if ``asymptotically stable'' is replaced by ``stable''? Explain.