2. (a) The function y(x) is defined implicitly by the equation y cos I - ry = 1+x2. Calculate dy /dr in terms of r and y. (b) Evaluate the integral 13 log r dr. (c) Show that 4x - 11 x2 - 71 + 10 dx = log 10. (d) Find the solution of the differential equation dy - x(y2 +9) which satisfies y = 3 when r = 0