1. Let D be the region lying between the hyperbolas xy = 1, xy = 2 and the lines y = x,y = 4x. Evaluate the integral Double integral D yxdA.
Key words: double integral, changing variables, Jacobian.
2. Let C be the portion of the ellipse x^2/4 +y^2/9 = 1 lying the second quadrant. Evaluate the integral C xyds.
Key words: a path integral, parametrization of a curve