3-2. Prove Theorem 3.2. Theorem 3.2 Let I S R be an open interval, xe I,...
Let U be an open subset of R". Let f: UCR" ->Rm. (a) Prove that f is continuously differentiable if and only if for each a e U, for eache > 0, there exists o > 0 such that for each xe U, if ||x - a| << ô, then |Df (x) Df(a)| < e.
#23 22, Use the definition of limit to prove Theorem 3.5. 23. Use Theorem 3.5 to prove that lim x? cost(1/x)-0. In addition, give a proof of th result without using Theorem 3.5. THEOREM 3.5 Squeeze Theorem for Functions Let I be an open interval that contains the point c and suppose that f, g, except possibly at the point c. Suppose that g(x) s f(a) s h(x) for all x in I If limn g(x)-L = lim h (x),...
1 xe Let f(x)={? x 8. Prove that f(x) continuous only at +1. Let f(x)= $3.x xs! x >1 Using the definition prove lim f(x)=1 and lim f (x) = 3 x>17 11°
(Proof of the Squeeze Theorem for Functional Limits). Let f.g, h: A R be three functions satisfying f(x) < 9(2) < h(r) for all re A, and suppose c is a limit point of A and lim; cf(x) = L and lim -ch() = L. Prove that lim.+c9(x) = L as well.
1-> X- Let f :S → R and g:S → R be functions and c be a cluster point. Assume lim f (x), lim g(x) exists. Using the definition of the limit prove the following lim(af (x) + Bg(x)) =a lim f(x) + Blim g(x) for any a,ßeR xc XC X-> b. lim( f(x))} = (lim f(x)) f(x) lim f (x) c. If (Vxe S)g(x) # () and lim g(x)() then prove lim X-C XC 10 g(x) lim g(x) X-C
Proof Theorem 65.6 (a generalization of Dini's theorem) Let {fn be a sequence of real-valued continuous functions on a compact subset S of R such that (1) for each x € S, the sequenсe {fn(x)}o is bounded and топotone, and (ii) the function x lim,0 fn(x) is continuous on S Then f Remark that the result is not always true without the monotonicity of item (i) Šn=0 lim fn uniformly on S Theorem 65.6 (a generalization of Dini's theorem) Let...
a) Prove the following theorem: Let f:(x,d)-(Y,p) be bijective and continuous. Then f is a topological mapping iff: VUCX: U open = f(U) open in Y. b) Þrove the following theorem: Let f :(X,,d) (X ,d) and f:(X2,d)) (X 3,d) be topological mappings, Then f of, (the composition of the two functions) is topological.
1 Let f: R R be a continuously differentiable map satisfying ilf(x)-FG) ll 리1x-vil, f Rn. Then fis onto 2. f(RT) is a closed subset of R'" 3, f(R") is an open subset of RT 4. f(0)0 or all x, y E 5) S= (xe(-1,4] Sin(x) > 0). Let of the following is true? I. inf (S).< 0 2. sup (S) does not exist Which . sup (S) π ,' inf (S) = π/2 1 Let f: R R be...
real analysis hint 13 Suppose fis a continuous function on R', with period 1. Prove that lim Σ f(a)-| f(t) dt 0 for every irrational real number α. Hint: Do it first for f(t)= exp (2nikt), k = 0,±1, ±2, 4.13 Let 2 be the set of functions of form P(t)-Σ_NQC2nikt. The equality holds for functions in . For given ε > 0, there is a P E 2 such that llf-Plloo < ε. Then
Theorem 2. Let E be an open subset of R² and suppose that fe C'(E). Let y(t) be a periodic solution of (1) of period T. Then the derivative of the Poincaré map P(8) along a straight line normal to r = {x E R x = y(t) - (0),O SE ST} at x = 0 is given by T P(0) = exp V. f(y(t)) dt. 4. Show that the system • = -y + (1 – 22 - y2)2...