Let $f:[0, \infty) \rightarrow \mathbb{R}$ be continuous. Find $f(2)$ if for all $x \geq 0$,
(i) $\int_{0}^{x} f(t) d t=x^{2}(1+x)$,
(ii) $\int_{0}^{f(x)} t^{2} d t=x^{2}(1+x)$,
(iii) $\int_{0}^{x^{2}} f(t) d t=x^{2}(1+x)$,
(iv) $\int_{0}^{x^{2}(1+x)} f(t) d x=x$.