Let E(x)=(x2+7)2−49.
(i) Show that E(x) can be expressed as the difference of two perfect squares.
(ii) Factorise E(x) completely, writing your answer as a product of linear or irreducible quadratic factors.
(iii) Hence find all real roots of the equation (x2+7)2−49=0. Present your answer in simplest form.