If $$x = \sqrt[3]{49}+\sqrt[3]{42}+\sqrt[3]{36}$$, then the value of $$x-\frac{1}{x^2}$$ is

A

$$2\sqrt[3]{42}$$

B

$$3\sqrt[3]{42}$$

C

$$\sqrt[4]{42}$$

D

$$4\sqrt[3]{42}$$