**Question **# 3. Integrate the following: \text { a) } \int x^{2} \sqrt[3]{x} d x \text { b) } x^{3} \int\left(x^{2}-5\right) d x \text { c) } \int \frac{x^{5}-2 x^{4}}{x^{2}} d x d) When the fixed cost of producing marginal cost is Cx=0.6x²+2x.x units of steel is C[0]=&$5500and its Find the cost function C(x) and determine the cost of producing 45 units.