(i) What is the rate of change of the area of a circle with respect to its radius / at / = 6 cm ?

(ii) Write the equation of the normal to the curve x² = 4y which passes through the point (1, 2).

(iii) If f(x) = 3x² +15x + 5, then find the approximate value of f(3.02).

(iv) Write the slope of the normal to the curve y= 2x² +3sinx at x = 0.

(v) The total revenue in Rupees received from the sale of x units of a product is given by R(x) = 3x² +36x +5. Write the marginal revenue, when x=15.