# uniform convergence and proof

Determine the uniform convergence and convergence of the series ∑▒〖〖(f〗_n),〗 where f_n (x)is given by the following: (The Weoerstrass M-Test will be needed)

a sin(x/n^2 ) b. 〖(nx)〗^(-2),x≠0,

c. 〖(x^2+n^2)〗^(-1) d. (-1)^n (n+x)^(-1),x≥0,

e. 〖(x^n+1)〗^(-1),x≥0 f. x^n (x^n+1)^(-1),x≥0.

Suppose (k_n ) is a decreasing sequence of positive numbers. If ∑▒(k_n sinnx ) is uniformly convergent, then lim(nk_n )=0.

© BrainMass Inc. brainmass.com March 4, 2021, 10:05 pm ad1c9bdddfhttps://brainmass.com/math/real-analysis/uniform-convergence-proof-297769

#### Solution Preview

Determine the uniform convergence and convergence of the series where

a b.

c. d.

e. f.

a)

We know for all x, we have

For any given x, is convergent hence the series is convergent.

Further, as for any x. Hence the convergence is uniform.

b)

Let x is not in (-1, 1). Then we have . Hence the convergence of is uniform.

Let x is in (-1, 1) but not equal to zero. Let us suppose, . Then y is not in (-1, 1). So, we have

For a given such y, we have . Hence the convergence is pointwise.

Now, does not exist. Hence the convergence is not uniform in the interval (-1, 1)

c)

Let us first calculate the point wise limit ...

#### Solution Summary

This post deals with uniform convergence and proofs.