Let P* be a refinement of a partition, P. Show U(P*, f, a) < U(P, f, a)

Let A and B be subsets of R which are bounded above. a. Show that sup(AUB) = max {sup(A), sup(B)}. Let y = sup (A U B), a = sup (A), and ß = sup (B)

Let f {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} → {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} be defined by f(x) = 2x if x 6. Select all the elements of f({5,6}). 01 3 2 4 Select all the elements of f-¹({5,6}). 3 04 Select all the elements of ƒ−¹(ƒ({5,6})). 3 04 2 Select all the elements of ƒ(ƒ¯¹({5,6})). 01 3 04 5 5 06 6 07 07 07 07 U O 8 8 8 8 9 9 9 ✔10 10 10 10

Let (¥,r) and (¥ ,4) be two topological spaces. Prove that a function f :(X .r)——(¥ ,A) is continuous if and only if the inverse image under / of every A- closed set is a r- closed set.