Let I be a closed interval and let 0 < a < 1. Let f: I → I satisfy the inequality
|f(x) - f(y)| ≤ a|x - y|
for each x ∈ I and y ∈ I. (Such a function is called a contraction mapping.) Prove that f is continuous on I.
Let x1 ∈ I and define xn+1 = f(xn) (n = 1, 2, …). Prove that the sequence ⟨xn⟩ converges and that its limit l satisfies l = f(l). [Hint: exercise 5.21(1).]