Paper 2, Section I, F

Topics In Analysis
Part II, 2017

Are the following statements true or false? Give reasons, quoting any theorems that you need.

(i) There is a sequence of polynomials PnP_{n} with Pn(t)sintP_{n}(t) \rightarrow \sin t uniformly on R\mathbb{R} as nn \rightarrow \infty.

(ii) If f:RRf: \mathbb{R} \rightarrow \mathbb{R} is continuous, then there is a sequence of polynomials QnQ_{n} with Qn(t)f(t)Q_{n}(t) \rightarrow f(t) for each tRt \in \mathbb{R} as nn \rightarrow \infty.

(iii) If g:[1,)Rg:[1, \infty) \rightarrow \mathbb{R} is continuous with g(t)0g(t) \rightarrow 0 as tt \rightarrow \infty, then there is a sequence of polynomials RnR_{n} with Rn(1/t)g(t)R_{n}(1 / t) \rightarrow g(t) uniformly on [1,)[1, \infty) as nn \rightarrow \infty.