Two polynomials are given:
f(x)=3x4−2x2+5,g(x)=−x3+4x.
Answer the following in the order given.
(i) Find the polynomial h(x)=f(x)−g(x) and write it in descending powers of x.
(ii) Determine the degree and leading coefficient of h(x).
(iii) Calculate the y-intercept of h(x).
(iv) State, with a reason, whether the graph of h(x) opens in both upward and downward directions or in only one direction.