Determine whether S = { (1,0,0) , (1,1,0) , (1,1,1) } Is a basis
for R^3 and write (8,3,8) as a linear combination of vector in
S.
Please explain in details how to solve this problem.
For an arbitrary ring R, prove that a) If I is an ideal of R,
then I[ x] forms an ideal of the polynomial ring R[ x]. b) If R and
R' are isomorphic rings, then R[ x] is isomorphic to R' [ x ].
1. Prove or disprove: if f : R → R is injective and g : R → R is
surjective then f ◦ g : R → R is bijective.
2. Suppose n and k are two positive integers. Pick a uniformly
random lattice path from (0, 0) to (n, k). What is the probability
that the first step is ‘up’?
a) Suppose f:R → R is differentiable on R. Prove that if f ' is
bounded on R then f is uniformly continuous on R.
b) Show that g(x) = (sin(x4))/(1 + x2) is
uniformly continuous on R.
c) Show that the derivative g'(x) is not bounded on R.
Let f : R → R be a function.
(a) Prove that f is continuous on R if and only if, for every
open set U ⊆ R, the preimage f −1 (U) = {x ∈ R : f(x) ∈ U} is
open.
(b) Use part (a) to prove that if f is continuous on R, its zero
set Z(f) = {x ∈ R : f(x) = 0} is closed.